Mercurial Australian Kyrgios sent shockwaves around Wimbledon five years ago with a spellbinding fourth-round victory over two-time champion Nadal.

Kyrgios, 24, has been infuriatingly inconsistent since then with his regular on-court misdemeanours overshadowing his ability to play the kind of audacious tennis that often has fans and rivals rubbing their eyes in astonishment.

Even regular observers have no clue which Kyrgios will turn up, not just match by match, but game by game -- as was the case against Jordan Thompson on Tuesday when he appeared to "tank" the fourth set 6-0 but rebounded to win the decider 6-1.

His mental unpredictability, according to Wilander, could undermine third seed Nadal's trademark intensity.

"This is the most dangerous situation you can have as a tennis player, if you are a Rafa Nadal," Wilander, an analyst for Eurosport, told Reuters on Wednesday.

"Kyrgios second round, green slippery grass, Centre Court, you lost to him five years ago.

"Nadal knows the talent that's there and Kyrgios knows that too, especially on a fast grasscourt.

"For Rafa this is anxiety level at the absolute highest."

The series between them is tied at 3-3 with Kyrgios winning a stormy encounter in Acapulco this year -- the fallout of which is still rumbling on.

Nadal accused Kyrgios of "disrespect" after that defeat while in a podcast interview Kyrgios said the Spaniard was nice when he wins but "super salty" in defeat.

Kyrgios said after his win over Thompson that there was "mutual respect" between himself and 18-time Grand Slam champion Nadal but they would not be heading to the local Wimbledon pub The Dog and Fox to chew the fat.

While Wilander says Kyrgios' outlandish shots will not upset Nadal's rhythm, what could disturb the 33-year-old is the Australian's "couldn't care less" body language.

"(Kyrgios') irrational point construction will not be a problem, but what will be a problem is when Nadal doesn't know whether he is trying," the Swede said.

"Nadal tries his best all the time, every point. But Kyrgios can spend 10 minutes looking like he would rather be walking down the King's Road. That's a disaster for Nadal who plays so seriously. It's irritating."

Wilander also believes there is method in Kyrgios's madness and that his unwillingness to get drawn into the kind of physical battle Nadal thrives on will be in his favour.

"Listen, he is a genius. He is a genius tactically. He is a genius physically, You will never see him sweat. He doesn't play tennis like that.

He plays tennis how he feels, emotionally and physically. When he gets tired he just throws in a couple of second serves that are not coming back. He doesn't care if he double-faults or not," he said.

"That's why the tactics are so hard against Kyrgios because no one knows what he is going to do.