LLEYTON Hewitt has anointed Rafael Nadal as a future grand slam champion -- but hopes his prediction does not materialise just yet.

Hewitt, 23, says the 18-year-old Spaniard will eventually triumph at Roland Garros, but will today focus on achieving his own career-best effort at the Australian Open.

Into the Melbourne Park round of 16 for the fourth time, Hewitt is yet to reach the quarter-finals.

And, with Nadal standing across the net, Hewitt's title hopes are squarely on the line.

"Doesn't get any easier, just another step up, I guess," Hewitt said after stopping Argentine Juan Ignacio Chela in four sets on Saturday night.

"From all accounts, he's destroyed a guy (qualifier Bobby Reynolds) who he probably should destroy.

"It's going to be a tough match. He's a worthy opponent, playing round of 16 in a grand slam, on any surface.

"And he's hungry, he really is.

"He loves playing big matches. That's something I really respect in a young guy like him.

"He played (Andy) Roddick at the US Open in a night match and I thought he handled himself really well in that situation.

"Davis Cup final in Spain, that's not an easy thing to do, to play in a final at such a young age. He handled it incredibly well.

"I don't think the situation is going to worry him too much, plus we had a tough match here last year in the third round."

Hewitt and left-hander Nadal have met twice, with Hewitt winning on both occasions.

The South Australian won in straight sets -- 7-6 7-6 6-2 -- at the Australian Open last year in a tense contest.

Hewitt repeated the feat in Toronto in August, dropping the first set before easing clear to win 1-6 6-4 6-2.

Ranked 56th in the world, Nadal has been earmarked as a future world No. 1 by compatriot and mentor Carlos Moya.

Hewitt places no store in Nadal's current ranking.

"He's a lot better player than whatever his ranking is, to not be seeded," Hewitt said.

"He's hungry, he's intense, he's competitive, he's all of that and he's good for the game.

"I'll be very surprised if he didn't win the French Open one day."

Nadal, who was pivotal to Spain's Davis Cup final victory last year, saved a match point in his second-round contest against Russian Mikhail Youzhny before bulldozing Reynolds.

Now for Hewitt.

"If I play very good match and Hewitt not his best match, I think I have a chance," Nadal said.

"It's very, very difficult match. But I am playing good.

"I am in the fourth round. (This) is my best result in one grand slam."