Grigor Dimitrov reached the US Open quarter-finals for the first time since 2019 with a five-set victory over Andrey Rublev, whose angry outbursts threatened to mar an enthralling match in New York.

Bulgaria's Dimitrov won the first two sets before surviving a comeback attempt from his Russian opponent to seal a 6-3 7-6 (7-3) 1-6 3-6 6-3 victory.

The ninth seed, who made the semi-finals at Flushing Meadows five years ago, will face Frances Tiafoe in the last eight.

"I think after the first couple of sets, he started playing amazing," said Dimitrov.

"There's not much else I could have done. I felt I had to pull the reins back a little bit and wait for an opportunity.

"I think that was the big difference today, and after that, I ran with the match, but it was very, very challenging."

Victory is just reward for the 33-year-old's calm composure as Rublev's antics once again took centre stage in the early stages of the match.

He required medical attention just five games into the match after slamming his racquet against his hand and frequently screamed and ranted in rage during the fourth-round encounter.

He displayed similar behaviour at both the French Open and Wimbledon earlier this year, while at March's Dubai Tennis Championships he was disqualified for unsportsmanlike conduct after screaming in the face of a line judge.

American Tiafoe delighted a lively home crowd with a 6-4 7-6 (7-3) 2-6 6-3 victory against Alexei Popyrin, who knocked out Novak Djokovic in round three.

Elsewhere, American Taylor Fritz came from behind to beat eighth seed Casper Ruud of Norway 3-6 6-4 6-3 6-2.

The 12th seed will face Alexander Zverev in the quarter-finals after the German beat American Brandon Nakashima 3-6 6-1 6-2 6-2.

Within just a handful of games, 26-year-old Rublev's frustrations had already started to boil over, the first signs of his brewing anger showing as Dimitrov broke for a 3-1 lead.

In the following game, the sixth seed slammed his racquet against his shoes and drew blood from his own hand after an error before his opponent consolidated his break.

Rublev called the trainer on to see to the bleeding cut on his left hand at the change of ends and, still troubled by his self-inflicted injury, failed to convert three break points in the next game.

And as Dimitrov served out the opening set, the Russian screamed at the ground, the crowd on Arthur Ashe Stadium stunned into silence by his latest outburst.

The second set looked to have brought a calmer Rublev. In the opening game, he had his back against the wall at three break points down but stayed focused as he fought back to hold.

But after missing two break points of his own in the fourth game, he missed what should have been a sitter of a volley for the advantage and started furiously ranting, the sound amplified under the closed stadium roof.

Despite his irritation, Rublev was playing well and finally got the break he had been seeking for 5-3 as an error-strewn Dimitrov buckled under relentless pressure with multiple double faults.

But Rublev was left laughing in disbelief at his own mistakes as he let slip a 30-0 lead when serving for the set and allowed his opponent the immediate break back.

More errors then creeped in in the tie-break, the Russian squandering a 3-1 lead as six successive points went Dimitrov's way to wrap up the set for the Bulgarian.

It was at that point that Rublev's mentality seemed to switch, and in the third set, Dimitrov started to wilt and found himself a double break down as his much calmer opponent mounted his comeback attempt.

And though Dimitrov put up more of a resistance in the fourth set, it quickly went the same way as Rublev forced a decider.

The tables turned in the fifth set, however, as Dimitrov found another level.

He sealed the deal by serving out the match to love, a Rublev backhand finding the net to give Dimitrov an eighth Grand Slam quarter-final berth.

Zverev continued his push for a first Grand Slam title by coming from a set down to beat Nakashima.

The 27-year-old responded impressively to losing the first set as he raced through the next three.

Nakashima claimed the crucial break late in the first set and saved four break points as he served it out.

But Zverev, seeded fourth, hit back immediately in the second, quickly going up 5-0 and he carried that momentum through the remainder of the match.

He hit 51 winners and did not offer so much as a single break point to Nakashima in the last three sets.

"I was extremely defensive in the beginning of the match and Brandon played an awesome first set," Zverev said.

"I knew I had to step up my game and play more aggressive."