Andrey Rublev has begun his ATP Dubai Championships title defence with a 7-5 6-2 win to spoil Filip Krajinovic's birthday.

Krajinovic, who turned 31 on Monday, had looked set for a dream day, surging 5-2 ahead before the second-seeded Rublev reeled off 11 of the next 13 games.

Rublev next faces Alejandro Davidovich Fokina, who beat Malek Jaziri in straight sets in the Tunisian's final professional match.

Earlier, Australia's Thanasi Kokkinakis continued his promising start to the year by beating France's world No.73 Quentin Halys 6-4 7-6 (11-9).

Kokkinakis has bounced back well after his heartbreaking defeat in five sets by Andy Murray at the Australian Open, winning a Challenger title in Bahrain, where he beat Jordan's Abedallah Shelbayh in the final.

Alexander Zverev beat the Czech Republic's Jiri Lehecka 4-6 6-3 6-4.

Lehecka won the pair's first match-up in January in Sydney, and beat Rublev in Doha last week before blowing five match points in the semi-final against Murray.

Zverev is still waiting to win consecutive matches this year in his comeback from an ankle injury.

"These kind of matches are extremely important for me right now," Zverev said.

"I found a way to win."

Murray, the 2017 Dubai winner, pulled out of the event citing a sore hip after toiling to reach the Doha final on Saturday.

He lost in Qatar to Daniil Medvedev, who is seeded third in Dubai.

Top seed Novak Djokovic will play his first match since winning the Australian Open when he takes on Czech qualifier Tomas Machac on Tuesday.