Australian Nick Kyrgios has explained the reasoning behind his courtside rant against Radu Albot at the US Open.

Kyrgios edged past Moldovan Albot with a 7-5, 2-6, 6-4, 6-2 win, but the 23-year-old struggled, which led him to break into a rant as temperatures reached highs of 35C at the Louis Armstrong Stadium.

Kyrgios was heard yelling on the US Open court to the supporters box, shouting: "I’m f****d, my legs are f***ed. I'm cooked, I'm f***ing done. I can't play.”

After the Australian pulled through after four sets he would later go on to explain that his on-court antics ‘keep him relaxed.’

“I knew it was going to be a tough match,” Kyrigios said. “I’m just happy I got through it, but right now I just want to get something to eat. I'm hungry.”

Although Kyrgios put down his antics as tactical, not everyone was so willing to accept this statement, as Roger Federer took aim at the 23-year-old claiming he needed to ‘slow down’.

“I think he finds it hard to not do any of those tricks,” Federer said on ESPN.

“Like myself, to some extent, we need the fun, we need the drop shot, we need some variation to everything, but he takes it to the next level.

“I get it, but it’s hard for him.

“At one point, you’d think that it has to slow down a little bit.

“Usually it happens after your teenage years are over, but it’s been a few years and it seems like it’s getting more and more extreme, which is quite interesting.

“I think he very well knows, deep inside of himself, what he also needs to do.”

Kyrgios will now turn his attention to the round of 64 where he will meet Frenchman Pierre-Hugues Herbert, who booked his place in the next round after beating Indian Yuki Bhambri in straight sets.