Top seed Kei Nishikori dispatched the "tricky" Benoit Paire 6-4, 6-3 on his debut at the Dubai Championships on Tuesday, while Marin Cilic was knocked out by Gael Monfils.

"It's never easy playing Benoit, of course. Great serve, great backhand. Tricky player. Good dropshot, good touch," said Japan's Nishikori.

Asia's top player, the world No. 6, will meet Hubert Hurkacz in the second round.

The top seed stands 12-2 for the season after a title in Brisbane, reaching the Australian Open quarter-finals and the semis this month in Rotterdam.

Meanwhile, third seed Cilic became the highest seed to exit so far as he went down to Monfils, with the Frenchman storming through a decider to win 6-3, 4-6, 6-0.

Cilic, the 2014 US Open winner, has made a slow start this season and is playing in just his second event of 2019 after a knee injury.

The seeds continued to tumble as eighth seed Daniil Medvedev has also crashed out in the opening round.

For rising Greek star Stefanos Tsitsipas, title-winner in Marseille at the weekend, he opened his campaign with a 6-4, 3-6, 6-3 victory over Australian Matthew Ebden.

"I'm happy that I was the first to find some solutions," said Tsitsipas, "He wasn't easy, he was playing pretty well. He has an Australian way of playing, coming to the net, serve and volley, playing flat, playing low."

The 20-year-old Tsitsipas is on the brink of breaking into the world's top 10 after a fantastic start to the year which also saw him beat Roger Federer en route to the Australian Open semi-finals.

(With input from Reuters and AFP)