Miami  - Desperate Rafael Nadal saved two of three match points with aces but couldn't hold off the momentum of hard-charging Argentine Juan Del Potro, taking a 6-4, 3-6, 7-6 (7-3) defeat Thursday in the quarter-finals of the Miami Masters.

The three-hour epic handed Del Potro his first victory over Spain's number 1 after three previous defeats. The youngster had not won a single set in the series before stepping onto court in front of an overwhelmingly Latin crowd in South Florida.

Del Potro will await a winner from the match between fourth seed Andy Murray and Australian Open semi-finalist Fernando Verdasco, now trying to save Spanish pride this week in a replay of a Melbourne match-up from 2007.

"It was an amazing disaster. I wasn't focused like usual," said Nadal.

"I don't usually lose up two breaks in the third on hard court. I haven't played well during this event. I didn't adapt well this time. It may have been a nice match for the crowd, but it was a terrible one for me. I played bad all the time."

Del Potro stayed with Nadal on baseline battles and broke the top seed's confidence after crawling back from the depths in the third.

Nadal salvaged three match points in the 12th game, notching his seventh and eighth aces, but couldn't hold serve in the ensuing tiebreak to exit on a forehand error.

On the women's side, teenaged Victoria Azarenka reinforced her recent move into the top 10, reaching a third final this season 6-3, 2-6, 7-5 over 2006 holder Svetlana Kuznetsova.

The Arizona-based Azarenka, 19, spent nearly three hours and needed four match points. She awaits the result of the clash later Thursday between sisters Serena and Venus Williams, who between them hold eight titles at their home event.

The Williams sisters will be playing for Serena's number 1 ranking, with a loss to Venus automatically letting Russian Dinara Safina into the top spot as of Monday.

"It feels great that all the work I've been doing is paying off," Azarenka said. "I was just trying to play every point from the beginning to the end. The second set didn't go so well for me, but I was still hanging in there."

Azarenka re-wrote a painful episode in her recent history, after holding a match point but losing to 2006 champion Kuznetsova in the 2008 round of 32 at Crandon Park.

Kuznetsova, now working without a coach and trying to find her way, said that she exceeded her modest expectations.

"I've not been winning a lot. Coming here I felt lost on the court. I didn't know what I was doing, so I was trying some new stuff and then some old stuff, and I was a little bit messed up, she said.

Azarenka said: "I was preparing myself for a long match. The last points and the last games was really, really tough. I'm just so happy that I found energy and that fighting moment. I had to fight, you know, no matter what. That was kind of adrenaline in the last games. I didn't have so much energy." (dpa)