MADRID — Grigor Dimitrov stunned Novak Djokovic in the second round of the Madrid Open on Tuesday, beating the top-ranked Serb 7-6 (6), 6-7 (8), 6-3 for the biggest win of his career.

MADRID — Grigor Dimitrov stunned Novak Djokovic in the second round of the Madrid Open on Tuesday, beating the top-ranked Serb 7-6 (6), 6-7 (8), 6-3 for the biggest win of his career.

The 28th-ranked Bulgarian saved three set points in the first before taking the lead, and Djokovic then appeared to hurt his right ankle when trailing 4-2 in the second. The Serbian player slipped on the baseline and winced in pain, then immediately called for a trainer and took a lengthy break to get treatment.

Earlier, defending champion Roger Federer looked comfortable on clay in his first match in two months, easing past Radek Stepanek of the Czech Republic 6-3, 6-3 to reach the third round.

In the women's draw, defending champion Serena Williams moved into the third round after beating Lourdes Dominguez Lino of Spain 6-2, 7-5.