Quote of the Day: Frances Tiafoe is "losing it" after getting LeBron James shout out

WATCH: Tennis Channel Live discusses the Americans left in the draw at the US Open

NEW YORK—Frances Tiafoe pulled off one of the biggest upsets of the US Open when he completed a 6-4, 4-6, 6-4, 6-3 victory over four-time champion Rafael Nadal on Monday night.

But after the three-hour and 34-minute battle, it was his priceless and emotional reaction after match point that captured hearts on Arthur Ashe Stadium.

“I felt like the world stopped. I couldn't hear anything for a minute,” Tiafoe recalled during his post-match press conference. “Even shaking [Nadal’s] hand, I don't even know what I said to him. It was such a blur.”

“I was already tearing [up],” he added. “I could barely see him and my team. Everyone was up. It was just wild. My heart is going a thousand miles an hour. I was so excited. I was like, Let me sit down.

“Yeah, I've never felt something like that in my life, honestly.”

And in the locker room, Tiafoe got another massive surprise: a congratulations tweet from none other than basketball megastar LeBron James.

Q. Did you see LeBron James' tweet?

FRANCES TIAFOE: Man, I was losing it in the locker room. Bro, I was going crazy (smiling).

Yeah, I mean, that's my guy. So to see him post that, I was like, ‘Do I retweet it as soon as he sent it?’ I was like, ‘You know what, I'm going to be cool and act like I didn't see it and then retweet it three hours later (laughter)’.

Obviously, like, he knows I'm a big fan of his. Got a text from [sports agent] Rich Paul as well. That's super cool, the fact they're watching right now.

Tiafoe will be aiming to come down to Earth quickly from the emotional high of his career’s biggest victory, because he’s got another huge challenge up ahead in the form of big-hitting Andrey Rublev.

The American has split his previous two matches against Rublev, with the Russian winning their most recent encounter in a comfortable straight sets in Indian Wells.

But Tiafoe will probably be taking inspiration from his other match against Rublev instead: a rollercoaster 4-6, 6-3, 7-6 (6), 4-6, 6-1 victory at last year’s US Open.