The second-ranked Djokovic squandered a 4-0 lead in the first set, but recovered to end Nadal’s latest winning streak on clay at 37 matches and earn the Serb his third straight victory over Nadal in finals this season.

Djokovic’s sixth title of 2011 allowed him to surpass Bjorn Borg’s 31-match season-opening run in 1980. He trails only John McEnroe’s 42-0 start in 1984.

“Probably it’s right at the top,” Djokovic said about beating Nadal on clay on Spanish soil.

“Under the circumstances I was playing an unbelievable match. … I stepped onto the court today believing I could win. I needed to be aggressive and it was a great match.”

Djokovic’s run of 34 straight wins since Serbia’s Davis Cup triumph in December is the eighth best of all time.

“I came up against a great player obviously — he’s having a monster year,” Nadal said. “He was better, you have to accept that.”

He also lost to Djokovic in the finals at Miami and Indian Wells this year.Petra Kvitova won her third title of the season by beating Victoria Azarenka 7-6 (3), 6-4 in the women’s final.

Streak

Nadal’s last defeat on clay came nearly two years ago against Robin Soderling at the French Open. He had won six titles on clay since, and this was only his seventh loss on the surface in 196 matches dating to 2005.

Nadal had split the last two finals here with Roger Federer, and beat the Swiss star in three sets in the semifinals on Saturday. But Djokovic proved too tough and avenged his 2009 loss to Nadal at the Magic Box arena, when the pair squared off in a record 4-hour plus semifinal.

Djokovic spent most of the past few seasons as the No. 3 player in the world behind Nadal and Federer, but started the year by winning the Australian Open and hasn’t looked back.

Yesterday, he was faced with what is widely considered the toughest test in tennis — Nadal on clay — and his victory is yet another signal that a permanent power shift may be in the works.

“I’m happy I can play the best tennis when I needed to and maybe that was lacking a lot in the past,” Djokovic said. “Maybe that’s what was missing against Rafa and Roger in the past tournaments.”

Djokovic raced out to 4-0 lead after Nadal netted to be broken for the second time.

“The game started terribly,” said Nadal, who also won here in 2005. “I have to play more aggressive with the forehand.”

The Spaniard broke back immediately and then pulled to within 5-4 after converting his second break point with a shot into the corner.

Nadal then saved three straight set points to even it before Djokovic took the set on his fourth try when his backhand took a lucky bounce on the net cord and left Nadal no chance.

In a match full of great shots, Nadal fired up the crowd with a spectacular between-the-legs lob to set up three break points in the first game of the second set. Nadal slammed a forehand down the line to break, but the stubborn Djokovic bounced right back to level in the next game.

“Every point took an average 10-15 rallies. I needed to work hard for my points,” Djokovic said.

The Serb earned $849,000 for the victory. Who can stop him now?

- additional reporting AP