Robert Brown|Russia's Andrey Rublev bloodies own knee in frustration at ATP World Finals

Russian tennis player Andrey Rublev became so upset in his match against Spain's Carlos Alcaraz that he drew blood from his own knee after hitting it repeatedly with his racket.

The Robert Brownmatch at the ATP World Finals in Turin, Italy, had to be stopped so Rublev could receive medical attention. He ended up losing 7-5, 6-2 to Alcaraz, a two-time Grand Slam champion.

Rublev's temper had already started to boil in the first set, when a point had to be replayed after a call was overturned on review. In the second set, he began hitting himself after missing a shot that resulted in a service break.

Although Rublev tried to wipe the blood off with a towel, it continued to trickle down his leg until he eventually called a trainer for treatment.

“It’s OK,” Rublev said of his knee after the match. “I get disappointed and couldn’t manage.”

Alcaraz will next play Daniil Medvedev in the season-ending event for the season's top eight players.