Madrid:David Nalbandian capitalized on an uncommonly error-prone Rafael Nadal and beat the second-ranked Spaniard 6-1, 6-2 on Friday to reach the semifinals at the Madrid Masters.
Nadal, playing in his first tournament in five weeks off to treat tendonitis in both knees hit five winners but had 29 unforced errors against Nalbandian.
"It's not an easy match to analyse. It's hard to play worse, which makes it a lot easier to go forward from this," Nadal said. "I didn't go in with a clear enough idea of the match I wanted to play."
It was Nadal's most lopsided loss since Julien Benneteau beat him 6-3, 6-0 in Lyon three years ago.
"I took advantage of all of Rafael's bad shots," Nalbandian said. "I think Rafael never felt comfortable out there."
The 33rd-ranked Argentine next plays Novak Djokovic, who earlier beat Mario Ancic of Croatia 7-6 (2), 6-2.
Roger Federer defeated Feliciano Lopez 7-6 (4), 6-4 to set up a matchup against 112th-ranked Nicolas Kiefer, who beat the fifth seed, Fernando Gonzalez, 7-6 (5), 6-2.
Lopez hit 28 winners in saving 10 break chances, but the Spanish wild card also committed 34 unforced errors against the top-ranked Federer.
"It would have been nice to break (more), but he served well and I didn't really have a chance," Federer said.
Nadal refused to blame his fatigue after Thursday's 7-6 (5), 6-4 win over Andy Murray.
"I don't want to come up with an excuse; when you lose, you lose. I think the result reflects enough," Nadal said. "It wasn't my day. I never felt good at any point."
Nadal was slow against Nalbandian's groundstrokes and was broken by the third game.
A double fault in the fifth set up another break chance for the Argentine with Nalbandian's forehand clipping the net to skip beyond Nadal for 4-1.
After holding at love, Nalbandian reached Nadal's overhead smash for a crosscourt winner and the set.
Nadal's inactivity appeared to manifest itself when he looped returns out of play or into the net, including on Nalbandian's break point chance in the second game.
It's Nalbandian's first semifinal of 2007.
"I'm feeling great after this match. I'll try to do the same tomorrow," the former Wimbledon finalist said.
Federer remained unbeaten in six meetings with Lopez.
"I created so many chances," Federer said. "Maybe he got a little frustrated midway through the second set and maybe he gave me some easier points. And maybe that kept it from going to a second tie breaker."
After both players held serve to start the second set, Federer scored the only break in the ninth game, pushing Lopez's volley past him to clinch it with a triple-break advantage. The defending champion won at love to complete the victory.
Djokovic's serve bailed him out of tight spots in the first set, and the third-seeded Serb broke twice in the second to close it out.
Djokovic, the US Open finalist who won Masters titles in Miami and Montreal this year, needed treatment on his left ankle before the second set after hurting it near the end of the tiebreaker.
Gonzalez earned a break in the third game against Kiefer and appeared on course to face Federer in a rematch of last year's final.
Kiefer immediately broke back and both held serve until the tiebreaker, where the German's powerful strokes frustrated Gonzalez into unforced errors.
The Chilean couldn't recover and Kiefer finished off Gonzalez in one hour, 39 minutes.