Fifth-seeded Grigor Dimitrov of Bulgaria saved two match points against an irate Paul-Henri Mathieu, beating the French qualifier 4-6, 7-6 (2), 6-2 on Monday to reach the second round of World Tennis Tournament in Rotterdam.

The 11th-ranked Dimitrov looked to be on his way out at 5-4 down in the second set but recovered to force a tiebreaker, which is when Mathieu lost his temper on the way to losing the match. He strongly objected to a replaying the first point of the tiebreaker and — after losing the set to an ace from Dimitrov — discussed the replayed point with a nonplussed Dimitrov for several moments.

Mathieu then turned his attentions to the chair umpire, remonstrating angrily and barking "do you understand tennis or not?" before finally walking off to the dressing room.

The break did him little good, however, as Dimitrov broke Mathieu's faltering serve at the start of the third set.

After the match, the 33-year-old Mathieu was still keen to continue the argument with Dimitrov, who tried in vain to explain his own point before the players eventually left the court.

The 23-year-old Dimitrov next plays Gilles Muller of Luxembourg, who beat 20th-ranked David Goffin of Belgium 7-6 (5), 6-7 (6), 6-3.

Earlier, Dominic Thiem advanced to the second round with a 6-4, 6-2 victory over sixth-seeded Ernests Gulbis.

The 47th-ranked Thiem broke his Latvian opponent three times and lost just four points on his first serve to claim his first victory this season following consecutive first-round losses.

Seventh-seeded Roberto Bautista Agut also progressed to the second round after defeating German wild card Alexander Zverev 6-4, 6-1.

Simone Bolelli breezed past Lukas Rosol 6-3, 6-1 and will next face either second-seeded Milos Raonic or qualifier Andrey Kuznetsov.