While Novak Djokovic struggles, Rafael Nadal keeps impressing.

Djokovic lost again on Wednesday, this time falling to 140th-ranked Martin Klizan 6-2, 1-6, 6-3 in the second round of the Barcelona Open.

Nadal, however, won again. He beat Roberto Carballes Baena 6-4, 6-4 for his 10th win in 11 ATP Tour matches this season.

Djokovic is trying to return to form after a lingering right elbow injury. He hasn't made it past the last 16 in five tournaments this year.

The 12th-ranked Serb got off to a slow start against Klizan but rebounded to force a third set. He was then broken while trailing 4-3, allowing the Slovak to serve out for the victory.

"It's a great feeling, amazing," said Klizan, who had never beaten Djokovic in four previous matches. "I know that he didn't play top tennis but a win is a win and I'm happy to be in the third round. I always play good tennis in Barcelona, I'm just enjoying it."

Djokovic decided to play in Barcelona after losing to Dominic Thiem in the third round of the Monte Carlo Masters. He also lost in the second round in Miami and in Indian Wells, and failed to advance past the last 16 at the Australian Open.

Nadal, coming off his 11th Monte Carlo title, trailed early in his match but closed it out to reach the third round.

The top-ranked Spaniard has won 38 consecutive sets on clay, extending his own record. He has won 32 of his last 33 matches on the surface, including 15 straight.

Nadal will next face Guillermo Garcia Lopez of Spain, who defeated Kei Nishikori after the Japanese player retired because of an injury.

Nadal needs to win his 11th Barcelona title this week to retain his No. 1 ranking.

Earlier, second-seeded Grigor Dimitrov defeated Gilles Simon of France 6-2, 6-1, while third-seeded Thiem beat qualifier Jaume Munar 7-6 (8), 6-1.