Australian teenager Kyrgios continued his dream Wimbledon debut by defeating 68th-ranked Czech Jiri Vesely 3-6 6-3 7-5 6-2 in the third round on Sunday.

In doing so he set up a last-16 showdown with 14-time major champion Nadal on Tuesday, a match likely to be played on the All England Club's famed Centre Court.

Wildcard Kyrgios, ranked 144th and at 19 the youngest man in the draw, believes anything is possible but a win would rank among the biggest upsets in Wimbledon history.

However, Australian Cash, the 1987 champion, wouldn't be surprised to see Kyrgios take a set or two off Nadal, who has lost the first set in all of his three matches so far.

"I've watched Rafa play three times now, watched him very closely, and if Nick wants my advice I'd be more than happy to give it to him," Cash said.

"I think he's got some firepower to trouble him, to be honest.

"He's got nothing to lose and the firepower to do some damage.

"It's a big ask to say he's going to win or get more than a set but you never know.

"Either way, it doesn't matter. It's just a great experience for him."

Two of Nadal's majors have come at Wimbledon, in 2008 and 2010, but in recent years he's looked most vulnerable on grass - reaching the last 16 this year for the first time since 2011.

"He's not timing the ball as well as you'd like at the moment and I don't think his accuracy is quite there," Cash said after Nadal defeated Kazakhstan's Mikhail Kukushkin 6-7 (4-7) 6-1 6-1 6-1 on Sunday.

"He didn't return particularly well and I think that's where Nick is going to have a good advantage.

"He will get a chance to hit some short balls and go for it."

Kyrgios has served superbly so far, leading the tournament with 76 aces in just three matches. AAP