Defending champion Stan Wawrinka has been ousted in the first round of the Dubai Tennis Championships by was upset by world No.77 Damir Dzumhur 7-6 (7-4) 6-3.

This was No. 3-ranked Wawrinka's first match since his Australian Open semi- final loss to Swiss countryman Roger Federer.

He left Melbourne with a right knee injury and began regular practices only a week ago. Wawrinka said his knee was fine, but suggested he needed more matches to get up to speed.

"In practice, (I) start to be OK the last few days, but today I was missing a little bit of something," he said.

"He (Dzumhur) started also to play a bit better, to put a little bit more first serves in, to put a little bit more pressure on."

Wawrinka raced to a 4-1 lead early before Dzumhur was able to hit back to take the first set.

"Three games in, like, six, seven minutes, he was playing outstanding there. I couldn't even touch the ball," Dzumhur said.

But that was also the point when Wawrinka slowed down and showed signs of becoming tentative, and allowed the Bosnian into the match. In the tiebreaker, Dzumhur went 5-2 up, which was more than enough to secure the first set.

Dzumhur bolted to 5-1 in the second set, but became nervous when serving for the match. In the 10-point seventh game, Dzumhur served three double faults, and lost the third break point he faced.

He kept his composure when serving for the match two games later, setting up match point with a forehand cross-court volley, and watched Wawrinka sail a forehand long.

Marseille finalist Lucas Pouille had a much easier time of it, winning through to the second round with a 6-2 6-2 demolition of Czech Adam Pavlasek.

Things were equally easy for rising Brit Daniel Evans.

Evans, who conquered Bernard Tomic in the Australian Open third round and made the final in Sydney to start his year advanced with a 6-2 6-3 win over Germany's Dustin Brown.

He will now play Frenchman Gael Monfils in the second round, while Spain's Fernando Verdasco also made it through with a 6-2 7-5 win over fellow veteran Andreas Seppi.