Dimitrov, playing the final match of 19 on the schedule, stopped Javier Marti 6-2, 6-4 without facing a break point. He lost only seven points in nine games servicing and advanced with three breaks.
He draws Djokovic, who is 26-2 with three titles this year, in the second round.
No. 11-seeded Nicolas Almagro won the first set 6-4 and moved into the second round when Tobias Kamke retired while 12th-seeded Milos Raonic stopped Nikolay Davydenko 7-5, 7-6 (7-5) and 14th-seeded Kei Nishikori swept past Jurgen Melzer 6-3, 6-2 in 61 minutes.
John Isner survived a lengthy 7-5, 7-6 (10-8) decision over Guillermo Garcia-Lopez, saving the only break point he faced but only converted one of his own four chances. Kevin Anderson was on the court 53 minutes in a 6-2, 6-2 romp over Jesse Levin and Jerzy Janowicz had a solid 6-3, 6-4 win over Sam Querrey.
Biologists detail four new deep-sea 'killer sponges'
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards