Nick Kyrgios says it’s “pretty damn cool” to be playing Rafael Nadal for a place in the Australian Open quarter-finals, predicting a physical battle against “a hell of a player”.

The two men have had a running feud since the outspoken Australian called Nadal “super salty” and his “polar opposite” last year after the Spaniard complained he “lacks respect”.

But Kyrgios was keen to hose down any differences and focus on the task ahead after battling through the longest match of his career to beat Karen Khachanov 6-2, 7-6 (7/5), 6-7 (6/8), 6-7 (7/9), 7-6 (10/8) on Saturday evening.

“I don’t really dislike him. I don’t know him at all. Hell of a tennis player. Don’t know him as a person. I’m sure he’s okay,” he said, adding that there was “a layer of respect” between them.

“I’m super-excited honestly. Playing one of the greatest tennis players on centre court at your own Slam, it’s pretty damn cool.

“Obviously it’s going to be another physical battle. Nothing comes easy with him. He had a relatively routine (third round) match, so he’s going to be feeling good. I’m looking forward to it. That’s why you play, I guess.”

Nadal earlier gave a cool response when asked whether he liked Kyrgios.

“When he does stuff that in my opinion is not good, I don’t like,” said 19-time Grand Slam winner and top seed. “When he plays good tennis and he shows passion for this game, he is a positive player for our tour.”

The pair have faced each other seven times before, with the world number one holding a 4-3 advantage.

Their last two encounters have been close affairs, including at Wimbledon last year when Nadal prevailed in a pulsating and bad-tempered second-round match over four dramatic sets.

‘Too good’

During the clash, the Australian ranted at the umpire and twice served underarm, infuriating the Spaniard. Afterwards he admitted he tried, and succeeded, in hitting Nadal with a stinging forehand.

“At the end of the day, we’re two different tennis players,” said Kyrgios, who appears to be trying hard this year to turn a corner from his petulant past.

“We go about it completely different. After Wimbledon, I lost, I got beaten by the better player. I shook his hand, looked him in the eye and said, ‘Too good’.”

But he took a lot out of that match, which he plans to put to good use on Monday, with the winner facing either France’s Gael Monfils or Austrian fifth seed Dominic Thiem for a semi-final berth.

“Every time you put up a battle like that against Rafa, you’re going to take confidence from it. Two tough tiebreaks. There’s nothing in that match really,” he said.

“He changed up his game plan a little bit. I’ll probably expect him to serve a little bit more to my forehand when I play him in a couple days. That’s what he did at Wimbledon.”

Despite playing for 4hrs 26mins against Khachanov, Kyrgios is confident he will be fully recovered and noted that he had enjoyed plenty of success before against left-handers like Nadal.

“Ever since juniors I enjoyed playing lefties. I feel like I kind of know what game plan I need to bring to be successful against them,” he said.

“I mean, Rafa is a different beast altogether.

“I kind of know his patterns. Everyone knows his patterns, can’t do anything about it. Federer knows his patterns. Everyone knows his patterns. He executes them at the highest level.”