Last time the two met, Nadal prevailed in a thrilling four-setter after Kyrgios was backing up from a night out at Wimbledon Village's Dog & Fox pub.

Six months on and the seemingly new and improved Kyrgios was promising to rest up and recover from the longest match of his career, a truly epic 6-2 7-6 (7-5) 6-7 (6-8) 6-7 (7-9) 7-6 (10-8) third-round triumph over Karen Khachanov that lasted a gripping four hours and 26 minutes.

"Physically I think I'll be fine. A whole day off tomorrow ... do all the right things," Kyrgios said after needing a medical time-out in the first set on Saturday night.

"I just served and felt my left bum cheek get sore. Feels better now, yeah.

"I'm super excited, honestly. Playing one of the greatest tennis players on centre court at your own slam, it's pretty damn cool.

"I'm looking forward to it. That's why you play."

Both men are playing down their bitter rivalry, but there's bound to be spice.

Branding Nadal "super salty" last year after the Spaniard accused him of lacking respect for his opponents and fans after serving under-arm during their most recent hardcourt encounter in Acapulco, Kyrgios is not ruling out using the sneaky, though legal, tactic again.

"If it gets in Rafa's head, then it's a success," Kyrgios said at this month's ATP Cup.

"Any time in a match where the opponent stops thinking about what he needs to do and starts focusing on external things like that, I think I've got an edge straightaway."

Kyrgios also caught Nadal's attention mimicking the top seed's meticulous pre-serve routine during his second-round win over Gilles Simon last week.

"I really don't care. I am here to play tennis. Honestly, I don't care at all. If it was funny, good," Nadal said.

For all the niggle and needling, Kyrgios maintains the utmost professional respect for the 19-times grand slam champion.

"I mean, (despite) what happens between us, he is an amazing player. He is arguably the greatest of all time," Kyrgios said.

"He is a champion. I will do everything I can and hopefully give everything I have and hopefully it will be enough."

It's been enough three times before, most famously at Wimbledon six years ago when the then-teenaged Kyrgios sprang the biggest boilover at the All England Club in quarter of a century by ousting the world No.1 in the fourth round.

"Ever since juniors I enjoyed playing lefties," Kyrgios said.

"I feel like I kind of know what game plan I need to bring to be successful against them.

"Rafa is a different beast altogether.

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

"But ... I just like playing lefties."

The Aussie underdog said he would take great confidence from his last-up loss to Nadal at Wimbledon.

"We had a pretty good match, 7-6 in the fourth set. Two tough tiebreaks. There's nothing in that match really," he said.

"Yeah, I feel good. Like I feel like my game is ready to go."

The winner will play either Dominic Thiem or Gael Monfils in Wednesday's quarter-finals.

Australian Associated Press