Roger Federer overcame Ernests Gulbis’ strong serve to reach the Qatar Open semifinals with a 6-2, 4-6, 6-4 victory.

Federer broke twice to take the first set with ease, but then hit two shots long in the 10th game of the second to let the Latvian level the match.

The players traded breaks to make it 3-3 in the third, before Federer capitalised on Gulbis’ errors in the 10th game to seal the win.

Gulbis finished with 13 aces - seven of them in the second set - and did enough to impress the Swiss No. 1 in their first meeting.

“I know that Gulbis is the player with the most potential right now,” Federer said. “Unfortunately, he doesn’t have the ranking he deserves. I took him very seriously. I wasn’t surprised by how he played today.”

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