Sub-par Serena, injured Djokovic limp to victory

For Serena Williams, it was a bad right elbow that led to some shaky serving and a dropped set.

For Novak Djokovic, first it was a balky right hip that needed treatment from a trainer; later came an embarrassing mistake.

For Andy Murray, it was a time warning from the chair umpire and losing a set for the first time in six matches against his opponent.

While nine-time French Open champion Rafael Nadal won in straight sets on a cloudy, windy Thursday, some red dirt got in the machine for three of the other biggest names at Roland Garros. That trio put those moments aside and reached the third round.

‘‘I know I’m capable of playing great tennis,’’ the top-seeded Williams said. ‘‘Just haven’t seen it yet.’’

Calling her performance ‘‘not professional’’, Williams was sloppy as can be for stretches in a 5-7 6-3 6-3 victory over 105th-ranked AnnaLena Friedsam, a German who had never won a grand slam match until this week. Williams committed 21 unforced errors in the first set alone, 52 in all.

Top-seeded Djokovic and Murray, seeded No 3, both will take on talented young Australians for berths in the fourth round. Djokovic faces 19-year-old Thanasi Kokkinakis, while Murray meets 20-year-old Nick Kyrgios.

Djokovic proclaimed the pain in his upper right leg ‘‘nothing serious, really’’ after taking a medical timeout late in the second set of his 6-1 6-4 6-4 win over Gilles Muller. For a few minutes, things did not look promising for Djokovic — prone on the court, getting massaged by a trainer. But he eventually moved a step closer to completing a career grand slam.

AP