Davydenko reaches last four

Nalbandian was dazzling against Ljubicic, going 5-0 up before winning the first set in 32 minutes.

A double break put him on the way in the second set, which he sealed with a thunderous serve in just 67 minutes.

In the day's other game, Federer survived a second-set nightmare to beat Argentine Guillermo Coria 6-0 1-6 6-2.

World number one Federer, chasing a third straight Masters title, crushed Coria in the first set but inexplicably fell apart in the second.

Coria had called the trainer to treat his left ankle at 5-0 down in the first set and looked a totally different player in the second.

I wish I could play like that more often but it's not easy David Nalbandian

But Federer regained his composure in the the third and broke serve in the sixth game before closing out the match on a Coria double-fault.

"In the end I'm happy I didn't use too much energy and came through," said Federer.

"I'm a bit disappointed about that second set but the win is what counts.

"I'm not 100% but I'll be OK for the weekend."

Nalbandian's win over Ljubicic was sweet revenge following his defeat to the Croatian in the semi-final of October's Madrid Masters.

The world number 12 only entered the tournament as a last-minute replacement for the injured Andy Roddick, but was delighted with the form he showed.

"I feel I played one of my best matches indoors," said Nalbandian.

"If I could play like that all the time of course my ranking would be higher. I wish I could play like that more often but it's not easy."

Ljubicic said: "I think I gave more than I had against Roger. There's really not much I can say.

"I couldn't do much really and (Nalbandian) was playing unbelievable.

"Really there's nothing to feel ashamed of. It's just disappointing to run out of gas just a couple metres to the finish line."