Grigor Dimitrov, Dominic Thiem pushed by Zverev brothers

Dominic Thiem and Grigor Dimitrov each were pushed to three sets before prevailing in the first round of the ATP's World Tennis Tournament in Rotterdam.

Thiem -- the tournament's second seed -- came back from a set down to beat rising star Alexander Zverev 3-6, 6-3, 6-4 in one hour and 44 minutes.

Zverev's brother, Mischa -- who stunned world No. 1 Andy Murray at the Australian Open -- won the first set against Dimitrov before the Bulgarian bounced back to win 6-7, 6-2, 6-4.

Third seed David Goffin had a 6-2, 6-3 triumph over Andrey Kuznetsov, and Richard Gasquet eased through to the second round with a straight-sets win over Viktor Troicki.

In the night session, Frenchmen Jo-Wilfried Tsonga booked his spot in the quarterfinals with a 6-4, 6-2 win over Gilles Muller.