Gael Monfils, the former world No.7 from France who is seeking to resurrect his career after a knee injury, has upset the seedings to reach the quarter-finals of the Qatar Open in his first tournament back.

Without a match for two and a half months, and now down at 77 in the rankings, Monfils edged out Philipp Kohlschreiber, the third-seeded German, by 6-4 2-6 6-4 in a two-hour contest full of absorbing, varied rallies.

These suggested no further problems with Monfils’ long-lasting ailment.

They also hinted at seriously renewed ambition for the 26-year-old Switzerland-based Parisian, who has often appeared to possess enough speed, serving ability, and inspirational flair to make the later stages of Grand Slams.

Now though, after a mental dip in the second set, it was greater consistency which enabled Monfils to prevail in the final stages of the deciding set, in which he snatched its only break of serve in the very last game.

“I didn’t know what to expect (from myself), but I produced good tennis,” said Monfils, whose biggest dilemma often seemed to be in regaining an instinct for how and when to mix patience with daring.

“I am physically a hundred per cent,” he insisted. “My knee is fine, and I moved well and I ran fast. I am very happy. Tonight I am pleased with my game.”

Monfils on Thursday has a last eight meeting with another German, Daniel Brands, a qualifier ranked outside the top 150 – with every prospect of making the semis.

Earlier Mikhail Youzhny, the number four seed, became another of six seeds to have fallen in two and a half days. His defeat created very different emotions within a 40-hour span.

Youzhny had been sharing a celebratory new year’s drink with his fellow Russian, Nikolay Davydenko, two days ago. Now he was trying to shrug off disappointment as he was beaten by his compatriot.

Davydenko, a 31-year-old former world No.3, was impressive during the second set of a 7-5 6-3 win, which suggested it may indeed be worth making one last major push for success.