Doha, Qatar, 6 January 2012 | AFP

Roger Federer is into his sixth semifinal in six tries at the ATP’s Qatar Open and a re-match with the man with whom he played one of the all-time great Grand Slam matches.

Federer’s 6-3 5-7 6-4 success against Andreas Seppi earned another meeting with Jo-Wilfried Tsonga, the Frenchman who came from two sets down to beat him at Wimbledon last year and lost to him only narrowly in the final of the ATP World Tour Finals.

“I am looking forward to playing him (Tsonga) again,” said Federer. “I hope it will be a good season for both of us.

“He’s always a nice guy to see play, and a nice guy off the court as well — so I hope we can live up to expectations.”

It was an up-and down performance on Thursday by the Grand Slam record-holder against the top 40 Italian who often rallied elegantly and expertly from the baseline without having overwhelming weapons.

Federer sometimes played a little ambitiously even for him in the second set, going 1-5 down, and recovering to 5-5 before somehow still losing it.

He broke serve early in the third set and held the advantage till the end, but his excellent first serving and passages of brilliance were marred by a total of 41 unforced errors.

Earlier Tsonga made possible the rematch he has longed for when he hurtled into the semifinals in little more than a hour.

The world number six wants to prove he can consistently compete on equal terms with the world’s best, and his 6-2, 6-1 win over Albert Ramos of Spain gave him a chance to start doing that.

Tsonga did little wrong against a surprise survivor who was increasingly pressured into attempting too much, thereby raising his ratio of mistakes to self-destructive levels.

The Frenchman also produced a combination of excellent serving, consistent ground-stroking, and conspicuous calm, all of which augured well for his meeting with Federer.

Tsonga’s celebration, extravagant for so relatively modest a success, may have indicated how much he is looking forward to playing the Grand Slam record-holder.

“Federer is the best player in the world, probably ever, and it will be difficult to play him,” Tsonga said.

“You have to be perfect. I have to play my best tennis.

“But I know I can do it. I have done it already.”

Tsonga was referring to the sensational win he had over Federer in the Wimbledon quarterfinals in July, and perhaps to his defeat with honour by 6-4 in the final set against the Swiss in the final of the ATP World Tour Finals at the end of November.

However the victory came on grass and the narrow loss indoors.

In Qatar, on an outdoor hard court, the circumstances are different again, with a tricky breeze and conditions which are sometimes on the slow side.