American tennis star Ben Shelton has brushed off an awkward exchange with opponent Flavio Cobolli after winning a tense clash at the Canadian Open.

The fourth seed overcame a 4-2 deficit in the final set to seal a hard-fought 6-4 4-6 7-6(1) win on Monday morning (AEST).

WATCH THE VIDEO ABOVE: Ben Shelton and Flavio Cobolli exchange words post-match.

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But the gripping match will be remembered for an interesting post-match conversation that began when the two players shook hands.

Shelton appeared to ask Cobolli about a gesture he made during the tiebreak. The Italian seemed to explain it wasn’t directed at Shelton, who immediately accepted the response.

But after they shook hands and went to their respective benches, things escalated. They went back to the net to continue the conversation.

The pair continued to talk about an apparent gesture, but it was unclear why the actual issue was.

Cobolli once again said it wasn’t directed at Shelton and added that he was frustrated at losing the match after leading in the final set.

Shelton, who was shirtless throughout the lengthy discussion, appeared to accept the Italian’s story, albeit slightly confused as well.

The pair eventually shook hands again and Cobolli left the court.

“He just made a gesture in the tiebreaker in asked him about it. He said it wasn’t towards me so we’re cool,” Shelton said on court after the match.

He was pressed again on the issue later, but said “there’s no story”.

“He said it wasn’t towards me. We’re good,” he said.

“We talked about it in the locker room, so I’m not going to answer any more questions about that.

“There’s no story, we’re good, that’s it.”

Shelton will face Aussie ninth-seed Alex de Minaur, who earlier beat Frances Tiafoe.

“Really difficult match. I was down and out, being a break down in the third, the way that he was playing,” Shelton said.

“I gave myself a second chance and I did a good job with it, kind of running from there. A really difficult opponent for me, someone who’s gotten me in three sets after I’ve won the first set twice.”