Zverev, Dimitrov advance at Monte Carlo Masters

WATCH: Grigor Dimitrov defeat Ben Shelton in the first round of the Monte Carlo Masters

Alexander Zverev started his clay-court season with a 3-6, 6-2, 6-4 win over Alexander Bublik to reach the second round at the Monte Carlo Masters on Tuesday.

The 13th-seeded German was playing on clay for the first time since a right ankle injury forced him to retire in the French Open semifinals against Rafael Nadal last year.

Zverev said he needed to "get the injury out of my head" and get used to sliding again.

"It felt awful at times to be honest, but he made me feel awful," Zverev said. "Tactically he played well, he didn't let me play my game at all. He didn't let me have my rhythm and he almost won the match, just a few points here and there."

Still, Zverev limited his unforced errors to nine and hit 21 winners on Court Rainier III to set up a match against Spaniard Roberto Bautista Agut in the next round.

Two-time semifinalist Grigor Dimitrov also advanced by beating American Ben Shelton 6-1, 3-6, 6-3. The 20-year-old Shelton made his debut at Monte Carlo and did not disappoint, testing Dimitrov in a tense contest that lasted more than two hours.

"It is one of those matches that I just needed to go through," Dimitrov said. "I played a lot of good tennis. There were a lot of positives to take out of that."

Dimitrov will next play Jiri Lehecka of Czech Republic.

Top-ranked Novak Djokovic will start his clay-court season against qualifier Ivan Gakhov later Tuesday. The 35-year-old Djokovic has not played since losing to Daniil Medvedev in the semifinals of the Dubai Championships five weeks ago, which ended the Australian Open champion's 20-match winning streak.

Stefanos Tsitsipas, aiming for a third consecutive title at the Country Club, takes on Frenchman Benjamin Bonzi.

Rafael Nadal, second-ranked Carlos Alcaraz, and seventh-ranked Felix Auger-Aliassime pulled out of the tournament.