The ITF shared the number of doping tests carried out on the players for 2017. The two top-ranked men's singles players, Roger Federer and Rafael Nadal had more than seven tests out-of-competition and more than seven tests in-competition.
Fellow top-10 players, Marin Cilic, Grigor Dimitrov, Juan Martin del Potro, and other players like Fabio Fognini and Andy Murray also underwent a similar number of tests for the year. Novak Djokovic, on the other hand, underwent between four and six tests during tournaments – he ended his season in July at Wimbledon – and more than seven out-of-competition.
Among the women, Serena Williams underwent around 1-3 tests both during and aside from tournaments. She played just two events, both in January, and then stopped competing due to pregnancy. Her sister Venus underwent around 4-6 tests while away from competition and more than seven tests during tournaments.
Maria Sharapova had over seven tests while away from tournaments and around 1-3 tests during tournaments. ALSO READ: Rafael Nadal: 'I won't fight to be No. 1 again. Federer did better than me'