Fed and Nalbandian through

The 25-year-old, who has never won the Madrid title, will face world number four David Nalbandian in the semis after the Argentine clinched a 6-4 6-7 7-6 victory over Marat Safin.

Although Ginepri played some high-quality tennis he was unable to match Federer on the crucial points and could not find a chink in the Swiss player's armour.

Federer pounced on the first break opportunity to go 5-3 up and then serve out to take the opening set. It was level-pegging in the second, but once again Federer moved up a gear at the crucial time to take a tiebreak.

The win was Federer's 80th of the year and extended his winning streak to 17 matches.

Nalbandian claimed only his second victory in eight matches against Safin with another gritty display to gain revenge for defeat in the 2004 final in Madrid.

"I think that I'm getting better with every match, but I'll need to be in even better form for tomorrow as it will be very tough," said the Argentine who has a 6-6 career record with Federer.

The 24-year-old, who edged a tight three sets victory over Tim Henman in the third round, took advantage of a succession of unforced errors to put Safin under early pressure and take the first set.

Safin's serve and forehand let him down at the start of the second and Nalbandian used his accurate two-handed backhand to help him manufacture a break in the first game.

BREAK BACK

Safin, who has recovered to 49th in the world after dropping out of the top 100 this year, rallied to break back in the fourth after Nalbandian had lost a challenge on the "hawkeye" replay equipment only to lose his serve again to trail 4-3.

The mercurial Russian, who made 74 unforced errors in the match, refused to fold, however, and broke when Nalbandian was serving for the match and then squared the match on a tiebreak.

There was nothing between the players in the final set and it boiled down to a tiebreak again, but this time Safin's serve failed him and Nalbandian sealed it 7-2.

Nalbandian moved up to fifth in the ATP Race with the victory over Safin and boosted his chances of qualifying for the defence of his Masters Cup title in Shanghai next month.

It will also give him confidence for the Davis Cup final against Russia in Moscow at the start of December when the pair are likely to meet again.

Later on Friday defending champion Rafael Nadal, who cruised past Tommy Haas on Thursday, meets Tomas Berdych of the Czech Republic, a player he lost two on their last two meetings.

Novak Djokovic, who beat British number one Andy Murray in the third round, takes on 10th seed Fernando Gonzalez who has played just one match this week having received a bye and a walkover on his way to the quarters.