Roberto Bautista Agut has overcame 22 aces from Reilly Opelka to beat the American 4-6 6-3 6-4 in the first round of the Qatar Open.

The Spanish player, seeded fifth, converted only two of 11 break points on Monday to win.

Bautista Agut, who reached the Montpellier final just over a week ago, will play Kazakhstan's Alexander Bublik in the second round after Bublik beat Indian qualifier Ramkumar Ramanathan 6-4 6-2.

Australian John Millman got off to a good start but lost to Georgia's Nikoloz Basilashvili 2-6 6-4 6-4 in his first round clash.

Surprise Australian Open semifinalist Aslan Karatsev had a relaxed return to the court with a 6-4 6-0 win against Qatari player Mubarak Shannan Zayid.

Karatsev's next match will be much more strenuous as he faces US Open champion Dominic Thiem.

Taylor Fritz was 4-2 down in the second set before beating Lorenzo Sonego 7-6 (5) 6-4. The American next plays sixth-seeded David Goffin or Filip Krajinovic.

Experienced French player Richard Gasquet set up a second-round match with Andrey Rublev, who's coming off a title win on Sunday in Rotterdam. Gasquet beat Slovenian qualifier Blaz Rola 6-4 6-4.

All eyes will be on Roger Federer in the second round as he makes his return after a year on the sidelines.

Federer had a first round bye and will take on either Frenchman Jeremy Chardy or Britain's Dan Evans in his first match back.