Roger Federer has blown a one-set lead and match point to lose to Nikoloz Basilashvili at the Qatar Open on Thursday.
In the second match of his comeback event after 14 months away from tennis, Federer secured the first set but eventually wilted and lost the quarter-final clash 6-3, 1-6, 5-7.
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On Wednesday, the 39-year-old marked his first match since losing to Novak Djokovic in the Australian Open semi-finals in January 2020 by defeating Britain's Dan Evans, also in three sets.
On Thursday, Federer had a match point in the third set before his Georgian opponent fought back to end the 20-time grand slam champion's tournament.
Despite the brutal loss, the Swiss champion said he was happy with how he played in his comeback event.
"I'm actually happy that I was able to play back-to-back three-set matches against top players. That's an important step forward to me," Federer said after the match.
"I'm not 100% yet. I can feel it, I can see it. From that standpoint, (what's) important is to be 100% by the grasscourt season... I'm still building up.
"So this is a stepping stone. I'm actually happy how I felt today on court overall.
"I was very happy with how I was able to handle the tough moments. I didn't feel like my game started to wobble the more important the points got.
"I think I was able to play how I wanted to play, so I think that's always a great sign and a great feeling to have."
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Federer initially eyed a return at last month's Australian Open, but slow progress in his recovery convinced him to skip the grand slam.
He then he said he would play in some events which would help him regain his fitness before Wimbledon, which he's won eight times.
"We've just got to take a real good look at the schedule and... see how much workload the body and knee can still take, what's the best way to prepare for basically the beginning of the season for me, which is the grasscourt season," he added.
Federer later announced he will not play in Dubai, an ATP 500 event which begins on Sunday.
On Thursday, fellow 20-time grand slam champion Rafael Nadal announced his withdrawal from Dubai.
After 14 months out and two knee surgeries, Federer impressed in the first set against the Georgian but then struggled to move as freely.
"He was always my idol, and I am sure he is to many tennis players and fans, so I am unbelievably happy," said Basilashvili.
"I'm very happy that he's coming back and playing again.
"Of course to win against him it's a dream come true. He was an idol."
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