Tennis doubles represent a special attraction for spectators as well as players. Almost all professional tournaments organised by the Association of Tennis Professionals [ATP] and the International Tennis Federation [ITF] include doubles draws (Martinez-Gallego et al., 2021c; Borderias et al., 2024; ATP, 2024; ITF, 2024). Changes in team competition formats (e. g. Davis Cup and ATP Cup) increase the importance of doubles while making doubles play the deciding point (Martinez-Gallego et al., 2021a). Interestingly, due to the specific skill demands in tennis singles and doubles an increasing number of tennis players on ATP tour are specializing on doubles or mixed doubles competition which comes along with a negative correlation between doubles and singles ATP ranking (r=-0.5, February 2025) and only 15 from the top 100 doubles ranked players are ranked beyond the top 1,000 in ATP singles ranking (https://live-tennis.eu).

Due to the rules and regulations, the doubles game has several differences compared to singles. Doubles are played in pairs, which implies a decision-making during the game between the players (Borderias et al., 2024). Players not only have to watch the ball but also their partners and opponents, demanding a higher perceptual skill compared to singles (Carboch et al., 2014; Carboch & Kocib, 2015). The court dimensions include added alleys, but the space per player is smaller, affecting movement, positioning, physiological demands, timing, and training. Communication between players is crucial, as it can determine the outcome of a match and is essential during and between points (Lausic et al., 2009; Kocib et al., 2020; Martinez-Gallego et al., 2021b). Nowadays, the scoring system at the international level differs from singles, featuring the best of two tie-break sets and a match tie-break, along with the no-ad rule. In contrast, Grand Slam doubles matches are played in a best-of-three tiebreak sets format with advantage sets, like singles (Pollard & Pollard, 2010; Borderias et al., 2024).

Although tennis doubles hold considerable importance in professional tennis, studies on this subject are limited. Research on doubles has primary focused on match structure (Martinez-Gallego et al., 2020), communication (Lausic et al., 2009), scoring systems (Pollard & Pollard, 2010), time characteristics (Martinez-Gallego et al., 2021d), and technical facts like serve efficiency between male and female athletes (Carboch & Kocib, 2015), and volley positions (Martinez-Gallego et al., 2021a). Only one article by Black & Van de Braam (2012) outlined changes in the modern double’s tactics over the years due to increased ball velocities, which impact the net game. However, none of the studies used notational match analysis to quantify this evolution. Therefore, we compared tactical characteristics in professional men´s tennis doubles in two samples of matches collected at least 20 years apart using the same self-programmed notational analysis software. We hypothesized fundamental game structural changes relevant for training prescription.

Stroke Pattern: Rally length (3.7 ± 0.3 vs. 4.2 ± 0.5 strokes per point, p<.001) increased significantly between D_<1990 and D_>2010. The mean percentage of serves (32.5 ± 3.9 vs. 23.8 ± 3.5 %, p<.001) and volleys (25.1 ± 4.0 vs. 17.3 ± 5.7 %, p<.001) decreased, while the mean percentage of groundstrokes substantially increased (8.8 ± 3.6 vs. 26.9 ± 7.0 %, p<.001) between D_<1990 and D_>2010. Additionally, more half volleys were played in D_>2010 compared to D_<1990 (3.3 ± 1.3 vs. 2.5 ± 1.2 %, p = 0.015) (Figure 3).

Figure 3 Percentage of the different stroke techniques (means and standard deviations) in professional men´s doubles in D_<1990 and D_>2010 .

Service: In D_<1990, almost every point beginning after 1^st and 2^nd serve was started by Serve & Volley (98.7 ± 2.0 %), while this was reduced to one third (33.9 ± 33.4 %, p<.001) with a high variation between players (Table 3). Meanwhile, I-formation and Australian formation percentage increased significantly from D_<1990 (3.5 ± 3.2 %) to D_>2010 (8.9 ± 9.0 %, p<.001). Serve direction remained constant with around two thirds of the serves played at the opponent’s backhand (64.9 ± 9.6 vs. 67.3 ± 8.6 %, p = 0.345). Additionally, the positioning of the serve partner remained relatively consistent over the years (Table 3 and Figure 4).

Return: In earlier times, significantly more returns were played from Zone 3 before the baseline inside of court (58.9 ± 13.2 vs. 27.7 ± 7.4, p<.001*) and more often the return was combined with a net attack called “Chip & Charge” (30.4 ± 17.7 % vs. 6.8 ± 6.0, p<.001) (Table 3). Also, the return partner´s position was more offensive in D_<1990. Return partners were positioned in 80 % of first serve points in offensive Zones 1 or 2 compared to 16,5 % in D_>2010. The starting position was more offensive before second serves in both groups, but the difference remained (Figure 4).

Volley: More recently, a strikingly higher number of volleys were played from a close distance to the net in Zone 1 (42.9 ± 10.9 %, p<.001) ensuring a high hitting point (84.0 ± 4.7), while in earlier times volleys were mainly played from Zone 2 (76.0 ± 13.1, p<.001) with a lower hitting point (Table 3 and Figure 4). Volleys are played almost equally while moving forward or from a standing position (p = 0.548) (Table 3).

Figure 4 Percentage rate of different on court positions for volleys (A), returns (B), serve partner (C), and return partner (D) in D_<1990 (white bars) and D_>2010 (grey bars). In Figure D, the dotted bars indicate the return partner position awaiting a 2^nd serve.

This is the first study on professional level men’s doubles in tennis quantifying tactical characteristics and their historical development over a period of more than 20 years. The data presented indicate a significant shift in the fundamental playing structure of tennis doubles and in multiple technical and tactical details. The main differences between earlier and more recent doubles characteristics consists in a lower but individually inhomogeneous frequency of the serve & volley strategy from the server, a move of the service partner closer to the net (because he is no longer responsible for securing the back field) and, a more defensive position of the return players, both, regarding return player position as well as return partner. These changes are coming along with an increase in stroke rate and importance of the baseline ground strokes while reducing net play, and consequently an extension of the rally duration (Figure 3 and Table 3). This striking development is even more remarkable since no major rule changes during the last decades and no significant change in the players anthropometrics have taken place. Since the social relevance and the prize money structure in doubles remain lower than in singles, these aspects also seem to have no impact.

The reasons for the observed changes can only be speculated and they are very likely diverse. Previous studies showed that the velocity of both, serves and groundstrokes significantly increased over the past decades (Fernandez-Fernandez et al., 2010), whereas the proportion of specialized Serve & Volley players in singles declined. There is a lot of evidence that the quality (power and precision) of the baseline groundstrokes has improved to such an extent that attacking the net in both, singles, and doubles is rarely successful (Black & Van de Braam, 2012; Martinez-Gallego et al., 2021c). It can be hypothesized that an improved physical performance and athletic of the players, as well an innovative racket technology are the main underlying explanatory factors. Apart from that, a change in teaching and learning philosophy of coaches and some well accepted ITF programmes promoting an earlier starting age in children's tennis (e. g. “Play and Stay” as well as “Tennis 10s”) may also play a role (https://www.itftennis.com). Due to the shorter stature and arm span of very young players, the net play is neglected in training and competition. Therefore, older players did not experience sufficient learning opportunities for developing the necessary skills to cover the entire court adequately (Schmidhofer et al., 2014). As a result, servers usually remain at the baseline after second serves, and only occasionally approach the net following first serves.

Generally, the dimensions of the playing field in doubles are in favour of a joint offensive at the net because of the reduced responsibility on half a doubles court (5.49m/player in doubles vs. 8.23m/player in singles). This may lead to a few doubles pairs still favouring a net attack strategy. Assuming that Serve & Volley is a key indicator for the basic strategy in doubles, one can observe extreme heterogeneity in the more recent sample (Table 4). It can be distinguished between doubles pairs that almost never or very rarely play Serve & Volley (n=9), those that use it about half of the points (n=3) and those that almost always play it, even following a 2^nd serve (n=3) (Table 4). Usually, but not always, the rate is higher after a 1^st serve. Some individuals tend to attack more often after the 2^nd serve, possibly because it allows more time to get to the net (e. g. Chela/Monaco, ARG). The table also shows a high consistency between multiple observations of a double pair (e.g. Petzschner/Kas, GER), like a fingerprint.

The Serve & Volley application does not seem to be a performance-differentiating feature compared to earlier times. For example, it is noticeable that one of the most successful pairs in our analysis and Champion at the ATP World Tour Doubles Finals (López/Granollers, ESP) did not complete a single attack. These tremendous variations bring uncertainty among coaches which strategies should be taught and applied. The decision is probably a balancing act between having a good serve and stable volleys as well as above-average height (speaks for Serve & Volley strategy) or by possessing exceptionally good groundstrokes, high speed and mobility and smaller body size (speaks for baseline strategy). Since both strategies can be successful, perfecting the chosen style seems to be more important by regularly participating in doubles tournaments with an experienced partner. While in D<1990 the singles and doubles ranking were correlated quite well (r=0.5), in recent doubles we found even negative correlations and only 15 players of the TOP 100 ATP doubles ranking are positioned beyond the TOP 1000 in ATP singles ranking. This indicates nowadays an increasing specialization in doubles competition.

Staying at the baseline after serve influences the return strategy. In D_<1990, doubles specialists returned almost exclusively from a position inside of court (Zone 3) to put the advancing server under time pressure (Figure 4). In more recent doubles, returns after the first serve are more often executed from a position behind the baseline. This change in return strategy might also be related to the faster serve velocity. Due to the greater distance from the net, the Chip & Charge strategy is now used in less than 10% of cases (Table 3). Also, the returner's partner is increasingly positioned further back during the first serve (Figure 4), meaning that the returning pair often defends from the baseline during the rally. In contrast, when the game starts with a second serve, the returning pair often adopts an offensive position. Since in these cases the server more often remains on the baseline, the classic, diagonally offset pattern of one net player and one baseline player leads to crossing to the opposite side, either by agreement or spontaneously, depending on the game situation. In addition, the I-formation or Australian formation are now more frequently used as variants (Black & Van de Braam, 2012; Kocib et al., 2020). In contrast, the basic structure in D_<1990 consisted of two net-players (serving pair) facing either one to two players at the baseline or two opposing net players (returning pair).

Both, the altered serving and returning strategy led to changes in the characteristics of the volleys. Previous volley demands in D_<1990 involved a lower contact point and a longer stroke distance to the net (Table 3, Figure 4). In contrast, current hitting positions are located closer to the net with a higher hitting point and mainly from a standing position. This is because players nowadays are less likely to bridge the gap from the baseline to the net during rallies and less often play the Serve & Volley strategy. The technical execution of the volleys has therefore changed completely. In contrast to the earlier, more guided movement under less time pressure, a volley with short movements and an extreme angle from a position very close to the net dominates today.

It must be emphasized that the study suffers from important limitations. The major one refers to the difference in the sample sizes (D_<1990 n=57 matches; D_>2010 n=8 matches). Furthermore, current data is missing because D_>2010 is already partially outdate. Finally, players from D_>2010 were lower ranked on ATP doubles ranking (Table 1). In total these limitations might potentially influence the results of the study and emphasises the importance of careful interpretation. On the other hand, the quantitative differences shown are so clear and highly significant that we see a relevant gain in knowledge despite the limitations mentioned. Even if a comparison to actual current data is unfortunately missing, the data shows the possible extent of historical changes in racket sports.