Gael Monfils, the former world No.7 from France who is trying to resurrect his career after a knee injury, scored arguably his best win for nearly a year to reach the Qatar Open quarter-finals in his comeback tournament.
It was hard to believe that Monfils is now down at 77 in the rankings and has gone two and a half months without a match, for he looked mobile, motivated, and unusually pragmatic while beating Philipp Kohlschreiber, the third-seeded German, 6-4, 2-6, 6-4 in two hours of absorbing, varied rallies.
These suggested Monfils may have rid himself of his chronic ailment. They also hinted at enduring potential for an unpredictably gifted 26-year-old player still with enough speed, serving ability, and inspirational flair to make the later stages of Grand Slams.
"I didn't know what to expect (from myself), but I produced good tennis," said Monfils, "I am physically a hundred percent," 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."
It is almost three and a half months since Monfils produced a similar win in Metz over Kohlschreiber, a top 20 player, and eleven and a half since he beat his compatriot Gilles Simon, who was then world number 12, in Montpellier.
This time it was new-found tactical flexibility and greater consistency which enabled Monfils to prevail in the final stages, as he snatched the only break of serve in the very last game.
"I was a bit scared when he (Kohlschreiber) was hitting the ball very fast and I had to adapt and change my tactic," he said.
"I tried to play a bit more loopy, to give me time and to make him play up there (higher bounce) because he has very very clean winners when I was playing under his belt."
Monfils also timed perfectly the one break of serve which decided the first set, snatching it in the last game as he punished Kohlschreiber for two dicey approaches to the net.
Monfils' standard dropped in the second set, apparently because he became upset at a time violation warning for taking too long between rallies.
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When twice break point down in the third game of the final set, though, Monfils' responses were different.
A forehand drive taken enterprisingly from the backhand tramline averted the first crisis and a heavy serve the other, after which his focus seemed to intensify.
Kohlschreiber by contrast appeared to commit himself to all-out attack on crucial points during the climax of the contest. It led to three important errors which more than anything cost him the match.
Monfils tomorrow has a last eight meeting with another German, Daniel Brands, a qualifier ranked outside the top 150 - with every prospect of making the semis.
There he could meet another compatriot, the second-seeded Richard Gasquet, who came back from 2-5 down in the final set to survive a bumpy two-hour 44-minute ride with Grega Zemlja, a Slovenian ranked outside the top 50.
Gasquet's 6-7 (7/9), 6-4, 7-6 (7/3) win saw him miss two set points in the first tie-break, save two break points early in the second set, throw his racket away angrily in the third, and twice stand within two points of defeat before wriggling to victory.
Sometimes he looked downbeat and disaffected, and it required adversity before his desire truly revealed itself.
"It was very tough. It was so close. It was very difficult," said Gasquet, who now plays Lukas Lacko, the world number 50 from Slovakia.
Two more seeds went out, making six altogether, the most notable being Mikhail Youzhny, the fourth-seeded Russian.
Youzhny was beaten 7-5, 6-3 by his compatriot Nikolay Davydenko, the champion here three years ago, but now making a last attempt to regain a place in the world's top 20 before retirement.
There was no trouble for top see David Ferrer, however, as the Spaniard coasted to a 6-3, 6-2 win over Germany's Tobias Kamke in the late match.