Tennis players hit very fast shots during matches and the opponent needs to hit the ball back within a limited time. The aim of this paper is to analyse the rally pace characteristics and the frequency of rally shots in the men's and women's matches at the Australian Open 2017. We analysed male (n=7) and female (n=23) matches at Australian Open 2017. We compared the (1) point duration;(2) number of rally shots; (3) time between the points; (4) rally pace; and (5) work to rest ratio. In spite of some small differences between the men's and women's matches, such as work to rest ratio (men 1:3,63±0,38; women 1:4,05±0,73), point duration (men 5,93±0,67 s; women 5,44±1,11 s) and rally shots number (men 4,85±0,48; women 4,47±0,72), none of these differences were significant. Both genders played at the same rally pace (while the ball is in the play), which was 1.2 s (mean ball flight time between the opponents). About 60 % of rallies were finished within the first four shots of the rally. Our findings could help coaches to utilize the practice sessions prior to the Australian Open tournament. VOLUME 13 | ISSUE 4 | 2018 | 749 was finished within the first 4 shots in about 60 % cases in both genders. These pieces of information could help coaches to utilize the practice sessions prior to the tournament. ACKNOWLEDGMENTThis study was written within the Programme of the institutional support for science at Charles University Progress, No.Q41 Biological aspects of the investigation of human movement. The authors report no conflicts of interest.

Tennis balls degrade after fast racket and ground impacts until they are changed after agreed number of games. The aim is to analyse the new (after the ball change) and used balls (prior to the ball change) match characteristics and the frequency of rally shots in matches in the Australian Open, French Open and Wimbledon in 2017. Paired samples t-tests and Cohen d were used to compare the point duration, number of rally shots, time between the points, rally pace and work to rest ratio among these tournaments. There was a significant difference in rally shots number played with the new balls (4.17 ± 0.86) compared to the used balls (4.60 ± 1.10) in female matches (p = 0.047); in males matches large effect size was found (d =-0.83) in the same variable with the new balls (4.44 ± 0.57) and used balls (4.95 ± 0.66), both happened in the Australian Open. No difference was found between the new and used balls in the rally pace in all the observed events. The Wimbledon match characteristics were least affected by the ball change. The ball degradation affected the match characteristic the most in the Australian Open, in terms of more rally shots, but not slowing down the rally pace. Our findings inform us how the ball change can affect the game performance in professional tennis.