McEnroe says his opponent should not be in the tournament

McEnroe, who came second in his group after losing his last game 7-6 (7-5) 7-5 to Cedric Pioline, says Rios, 30, is too young to be labelled a veteran.

Rios thumped Jeremy Bates 6-2 6-1, and the Briton now faces Goran Ivanisevic, who beat Paul Haarhuis 7-6 5-7 10-8.

Haarhuis v Sergi Bruguera and Pioline v Henri Leconte are the remaining games.

Rios reached the quarter-final stage with a 6-4 6-1 win over Pat Cash, and shrugged off McEnroe's comments about his age.

606: DEBATE It is not a stage for a 30-year-old to come along and strut his stuff IN 606: Have your say

"Maybe he is too old for it," he said. "They start saying this because I'm doing good. Maybe I'm too good for them."

But he said he did not fancy his chances against the 47-year-old three-times Wimbledon champion.

"I think I am not playing that good. I am missing too many balls. The court is too fast and the balls don't bounce enough.

"He's so fast I think he beats me in two sets."

Bruguera won his group, with Leconte clinching second place and a quarter-final spot by beating Thomas Muster 6-4 7-5.