Grigor Dimitrov has described his first-round exit at the French Open as a "big disappointment".

The Bulgarian, who was seeded ninth in Paris, was beaten in straight sets by world number 37 Ivo Karlovic on Tuesday.

Karlovic will now meet Austria's Andreas Haider-Maurer for a place in the third round.

"It's never easy to play against Ivo," Dimitrov told reporters. "Of course, it's a big disappointment for me. I liked my chances here.

"It was a very tough task for me today, especially if everything was going his way. I just couldn't find my rhythm and I couldn't [convert] any of the little opportunities that I had in the match."

Dimitrov beat Karlovic in straight sets earlier this month at the Italian Open before being knocked out in the semi-finals by Rafael Nadal.