MADRID — Rafael Nadal powered into the third round of the Madrid Open on Wednesday with a convincing 6-3, 6-1 win over Jurgen Melzer of Austria.

The defending champion made just three unforced errors playing on his favored clay surface in front of Spain's Queen Sofia, and converted all four of his break points.

The only break in Nadal's concentration came when a ball girl fainted and had to be carried off the center court for medical assistance in the second set.

Earlier, Novak Djokovic eased past Oscar Hernandez 6-3, 6-3. The third-seeded Serb fell awkwardly on his right knee on the clay surface at Madrid's new "Magic Box" tennis center in the second set, but was rarely troubled by his Spanish opponent.

"I was aware the court was quite wet because I saw they had watered it after the previous match. But I was lucky that I fell in a good way so there is no injury," Djokovic said. "It looked easy, but it wasn't. I played just well enough to win."

Djokovic never faced a break point in the match, while breaking Hernandez once in the first set and twice in the second.

Djokovic recently fell from third to fourth in the rankings, surpassed by Andy Murray despite winning the Serbia Open last week — the country's first ATP Tour event that he also helped organize.

"I try not to pay too much attention to rankings," he said. "But I am motivated to win back my third ranking position."

Juan Martin del Potro of Argentina also advanced when Tomas Berdych was forced to retire with a leg injury. The Czech player, who won his first title of the year at the BMW Open in Munich on Sunday, retired while trailing 6-2, 4-1.

In the women's event, Victoria Azarenka eased past Peng Shuai 6-4, 6-1 and Vera Dushevina stopped Francesca Schiavone 6-3, 4-6, 6-2.

In later matches, top-ranked Dinara Safina was to play Li Na, and Amelie Mauresmo was to faced third-seeded Elena Demetieva.