Nadal's best required against in-form Schwartzman

World number one Rafael Nadal was in superb form on Monday, but knows he cannot underestimate Diego Schwartzman.

World number one Rafael Nadal

Rafael Nadal knows nothing below his best will be acceptable when he faces Diego Schwartzman in the fourth round of the Australian Open.

Nadal breezed into the last 16 in Melbourne with a 6-1 6-3 6-1 victory over Damir Dzumhur on Friday.

Next up is 24th seed Schwartzman, who reached a career-high ranking of 25 in October and is through to the fourth round of a grand slam for just the second time in his career, reaching the last eight of the US Open in 2017.

And Nadal is wary of the Argentine, telling reporters: "He's a great player. He's a player that last year had an amazing year, and this year has started again playing so well.

"So already he has won three matches here, playing again at a very high level.

"He's a very complete player. Being honest, he's a player that if I don't play my best, probably I'm not going to win.

"He's a player that has all the shots, big control from the baseline, doesn't miss much. He's able to change direction easily.

"He's a player that already played the quarterfinals in the US Open. He's already in the fourth round.

"Tough one, and I need to play my best."