Roger Federer squandered three match points in a shock 3-6, 7-6 (7), 7-6 (5) second round loss to Russian qualifier Evgeny Donskoy at the Dubai Tennis Championships on Wednesday.
Federer, who has just won his 18th Grand Slam title at the Australian Open, failed to take advantage of three match points in the second set tiebreaker, losing two of the three opportunities on unforced errors.
Federer netted a forehand on Donskoy's one set point in that second set tiebreaker to extend the match to a third set.
The 116th-ranked Donskoy's dream of a quarterfinal berth seemed over when he forfeited his serve in the sixth game of the third set. But Federer wasn't able to close out the match when serving for it at 5-3 in the third, and then watched the Russian work his way to victory.
Federer led 5-1 in the third set tiebreaker, but Donskoy refused to fold.
Federer, who skipped last year's tournament because of arthroscopic knee surgery, was in the hunt for an eighth Dubai title.
The initial excitement in the match occurred with Federer leading 6-3, 3-4 - when one set of the court floodlights went dark. Fans in the crowd turned on their cellphone flashlights and start waving them in the air as if they were at a rock concert.
Both players then agreed to play on despite the problem and by two games later full lighting was restored.
Donskoy will play seventh-seeded Lucas Pouille in the quarterfinals. Pouille defeated qualifier Marius Copil 6-1, 6-4.
Earlier, top-seeded Andy Murray earned a place in the last eight with a 6-2, 6-0 win over Guillermo Garcia-Lopez.
Murray, playing in his first tournament since a fourth round defeat at the Australian Open last month, is showing no signs of being match rusty despite having to deal with a case of shingles.
The top-ranked Briton needed only 72-minutes to bypass the 97th-ranked Garcia-Lopez, saving the one break point he faced on serve at 30-40 in the first game of the match.
He broke Garcia-Lopez's serve for the first of five times in the fourth game of the first set.
''When I got the early break, pretty much was almost 30 minutes in and we'd only played four games,'' Murray said. ''Mentally, that was important for me, you know, to be up at that stage.
''I loosened up a bit after that and played really well.''
Murray, who only dropped one point on serve in the second set, will play Philipp Kohlschreiber in the quarterfinals. Kohlschreiber posted a 6-4, 6-4 second round win over Daniil Medvedev.
''Every time we have played, we have had a lot of close matches,'' Murray said of Kohlschreiber. ''He's a talented guy. He uses the angles of the court well. He plays with a lot of spin.''
Fourth-seeded Gael Monfils struggled with Dan Evans before securing a 6-4, 3-6, 6-1 win to reach the quarterfinals, where he faces left-hander Fernando Verdasco.
In an all-Spanish second-round outing, Verdasco upset sixth-seeded Roberto Bautista Agut 6-4, 3-6, 7-5.
Robin Haase upset fifth-seeded Tomas Berdych 3-6, 6-3, 6-4 to set up a quarterfinal meeting against Damir Dzhumur, who defeated Marcel Granollers 6-3, 6-4.