TURIN, Italy — US Open finalist Taylor Fritz frustrated Daniil Medvedev to the point that the Russian smashed his racket and was docked a point in a 6-4, 6-3 victory for the American in the opening match of the ATP Finals on Sunday.

Medvedev received two code violations from the chair umpire for his behavior.

"I get angry, frustrated. This time completely with myself, not with anyone. Just with myself," Medvedev said.

Later, top-ranked Jannik Sinner delighted his home fans with a 6-3,6-4 win over finals debutant Alex de Minaur.

The other group is set to start play on Monday, with Carlos Alcaraz facing Casper Ruud and Alexander Zverev meeting Andrey Rublev.

The top two finishers from each round-robin group advance to the semifinals.

The first set had been virtually dead even until the final game, when Medvedev hit three double-faults to hand the set to Fritz.

Medvedev then went over to his bench in a fit of rage.

Medvedev first slammed his racket against the bench, which resulted in a slight dent. Then he banged the racket again on the hard court inside Inalpi Arena and mangled the frame into a twisted mess — prompting him to toss it behind him.

"I have this every day, day in, day out, for like two, three years. Every practice is a struggle. Every match is a struggle," Medvedev said. "Now I feel zero pleasure in being on the court."

Midway through the second set, Medvedev was docked a point after he was broken and lost his cool again.

Medvedev then acted as if he was going to return serve with his racket facing the wrong way — he held it with the butt of the racket and the grip facing Fritz. That drew whistles from the crowd and Medvedev changed the racket position just before Fritz served.

"I was like, whatever, I've lost the match. I don't care,'" Medvedev said.

Fritz wasn't bothered by Medvedev's behavior.

"I was just laughing. I think he's really funny, to be honest," Fritz said. "Even when he's not playing me, he always cracks me up."

Fritz won long and memorable rallies at the start of each set, one included 26 shots and another that lasted 30.

"It was huge," Fritz said. "I kind of just fought through. I thought I did a solid job of showing him that I wasn't going to give him a lot of free points."

It was points like those that left Medvedev demoralized.

"Literally, everyone can stay in the rally with me right now," Medvedev said.

In September, at the US Open, Fritz became the first American man to reach a Grand Slam final in 15 years, but he lost the championship match to top-ranked Sinner.

The Californian is appearing at the season-ending event for the year's top eight players for the second time. Two years ago, Fritz beat Rafael Nadal in his opening match and lost to Novak Djokovic in the semifinals.

Fritz will get a rematch with Sinner later in the week. Djokovic, though, withdrew from the event.

Sinner's carrot-clad fans came out in full force.

Numerous spectators were dressed in orange or wore carrot costumes in honor of Sinner's symbolic vegetable — and his hair color.

Sinner, who lost the final to Djokovic last year, showed no signs of nerves when he opened with an ace for the first point of the match and promptly held at love.

The Italian was broken in his second service game, though. But, he responded by winning four straight games to take control as fans chanted on the changeovers: "Ole, Ole, Ole, Sin-ner, Sin-ner."

Sinner improved to 8-0 in his career against De Minaur.

"His ball speed, in my eyes, is so much higher than basically the rest of the people," De Minaur said. "It's very hard to find holes in his game."

Agencies via Xinhua