Second seed Dominic Thiem eased into the third round of the US Open on Thursday with a straight-sets win on his birthday.

The Austrian celebrated turning 27 by defeating India's Sumit Nagal 6-3, 6-3, 6-2 inside an empty Arthur Ashe Stadium.

Thiem will play 2014 US Open champion Marin Cilic in round three.

"He is a real champion, one of the very few active Grand Slam champions. He knows what it takes to win big matches. It's going to be tough," Thiem said of his next opponent. 

Nagal had become the first Indian man since 2013 to reach the second round of a Grand Slam.