Sixth seed Thiem - a semi-finalist at Roland Garros 12 months ago who has displayed impressive form in recent weeks - was the highest-ranked man in action and appeared to have been handed a tricky test against the world number 39.

However, Tomic was brushed aside with the minimum of fuss as Thiem triumphed 6-4 6-0 6-2 in one hour and 20 minutes.

Only one seed, Gilles Muller, exited the men's draw on a sweltering Sunday in Paris, while two of the day's most dramatic matches featured home players.

Lucas Pouille overcame compatriot Julien Benneteau in five sets, but another Frenchman, Quentin Halys, blew a two-set lead against Marco Trungelliti.

"It was very hot out there, so I'm happy that I won in three sets," Thiem said. "It was a tough opponent and a close first set, I guess. I was also a little bit nervous before the match, I have to say, and because of these circumstances I'm happy with my performance."

Australia's Tomic had no complaints.

 "I think game-wise on clay he's at a different level to me for sure," he said.

Muller has never made it past round two at Roland Garros and the 26th seed made another early exit, losing in four sets to Guillermo Garcia-Lopez.

However, there were no issues for the five other seeds who completed their matches on Sunday.

Grigor Dimitrov, Pablo Carreno Busta, Ivo Karlovic and Albert Ramos-Vinolas all made it through to round two, the latter pair the only members of that quintet to drop a set.

Pouille was also able to progress, although he certainly did not have things easy as Benneteau opened up a two sets to one lead and broke first in the fourth before losing his grip on proceedings.

The other seed to feature, Steve Johnson, was two sets to one up on Yuichi Sugita but trailed by a break in the fourth when play was suspended due to darkness.

Robin Haase could hardly have asked for a more routine start to his campaign, the Dutchman dropping just six games in a trouncing of teenager Alex De Minaur.

Haase could well find things tougher in round two, though.

His likely opponent is nine-time champion and red-hot tournament favourite Rafael Nadal, who begins his quest for 'La Decima' against Benoit Paire on Monday.