World number one Roger Federer [Images] swept through to the Hamburg Masters semi-finals with a resilient 6-4, 7-6 victory over Argentina's Guillermo Coria on Friday.

The 23-year-old top seed, who also beat Coria in last year's Hamburg final, was a break down in both sets and behind in the tiebreak but recovered to quell the 10th seed and set up a semi-final against Russian Nikolay Davydenko.

Davydenko beat Italy's [Images] Filippo Volandri 7-6, 6-4 while Belgian Christophe Rochus upset Argentina's Juan Ignacio Chela 3-6, 6-0, 6-3 to reach his first ATP Tour semi-final.

Rochus will face powerful French teenager Richard Gasquet, a 6-1, 6-2 winner over Italian Andreas Seppi.

Federer, who attempts to win the only grand slam trophy missing from his collection at the French Open starting in 10 days, punched the air in delight after lashing a forehand winner past Coria on match point.

"It's a message from me to the other guys for the French Open," said the Swiss who missed last week's Rome Masters with a foot injury. "I feel I'm back to very good form on clay."

Federer trailed 3-1 in the first set before unleashing some devastating backhands to help turn it around. He broke decisively at 5-4 with Coria, last year's French Open runner-up, twice hitting forehands out to lose the set.

The second set was interrupted for five minutes with Coria trailing 2-3 after a spectator fell ill in the stands, and the incident seemed to break Federer's concentration.

A careless forehand gave Coria break point soon after and, riding his luck, the Argentine mis-hit a forehand on to the line to lead 4-3.

Federer broke back for 5-5, however, and took the tiebreak 7-3 after overturning a 0-2 deficit as a tired-looking Coria, beaten in five sets in the Rome final last Sunday, lost his

nerve under pressure.

"I'm tired mentally and physically," he said. "If you are not 100 percent against Federer it's pretty much impossible to beat him."

FURIOUS VOLANDRI

Federer has now won 39 of his 41 matches this year and together with in-form Spanish teenager Rafael Nadal [Images], who missed the Hamburg event due to a hand blister, is the favourite for the French Open crown.

As the only one of the top 10 seeds left at Hamburg, he is also an overwhelming favourite to win his third Rothenbaum title in four years.

Davydenko, the world number 20 who reached the semi-finals in Barcelona last month, was a little fortunate to beat Volandri.

The Italian was furious after he lost the first set tiebreak 7-5 when his forehand was called out on set point despite replays suggesting it clipped the line. He then tossed away a 3-0 lead in the second set.

Gasquet, ranked 56th, could provide the main threat to Federer, whom he beat last month in one of the shock results of the season in the Monte Carlo Masters quarter-finals.

The 18-year-old from Beziers bludgeoned his way past Seppi, the world number 113, in a display of brute force in the centre court's evening game.

Rochus knocked out another Argentine, French Open champion Gaston Gaudio, in the previous round and turned his match against Chela on its head by reeling off eight successive games midway through the match.

• Complete tennis coverage
• All you want to know about Sania Mirza