Rafael Nadal is expecting a tough test against Gilles Muller after securing his place in the last 16 at Wimbledon with a convincing victory over Karen Khachanov on Friday.
Fresh from his triumph in the French Open, the Spaniard has been in fine form so far at the All England Club, and made relatively light work of Russian youngster Khachanov on Centre Court with a 6-1 6-4 7-6 (7-3) win.
Nadal has not lost a grand slam set since losing out to Roger Federer in January's Australian Open final, and the world number two will now take his place in the fourth round at Wimbledon for just the third time since winning the tournament in 2010.
However, the 31-year-old is under no illusions as to the challenge that Muller - who saw off Great Britain's Aljaz Bedene 7-6 (7-4) 7-5 6-4 on Friday - will present.
"He's one of the toughest opponents possible, on this surface especially," Nadal said.
"[Grass] is probably his best surface, without a doubt. He has a great serve, a great volley. He plays well from the baseline here.
"He's a tough, tough opponent. At the same time we are in the round of 16. You cannot expect to have an easy opponent. He played a lot on grass this year and has won more than anybody.
Nadal's career has been blighted by injuries in recent years, though the Spaniard is hopeful the injury woes are now in the past, and claims to have regained the confidence in his body.
"When you are having problems, you don't have confidence with your body, and then it is much more difficult to play well," he added.
"If you feel that you are healthy, then you feel confident that you can do whatever you want in terms of practice, and you can move without thinking, just thinking about the ball.
"That's very important because when you are losing a little bit of time thinking about how you have to put that leg there because of the pain, then it is almost impossible to concentrate."
Nadal will have two full days of rest before taking on Muller, with the pair set to meet on July 10.