Dimitrov pounded out six aces and didn't face a break point in a 6-2, 6-3 win over Robin Haase that took just 58 minutes. Dimitrov claimed 21-of-23 points when he landed his first serve and lost seven points over nine games serving.
Marinko Matosevic took a 5-7, 6-4, 7-6 (7-4) decision over Julien Benneteau in a match that lasted 2 hours, 41 minutes. Both players had four breaks, including one each in the third set to force the tiebreaker.
Marin Cilic came away a 6-7 (3-7), 7-6 (7-5), 6-4 winner over Denis Istomin, with his third-set break the only time either player dropped serve in the match. Jarkko Nieminen saved five break points in a 6-2, 6-3 win over James Duckworth in Monday's other first-rounder.