John McEnroe cruised through to the quarterfinals of The Masters Tennis presented by Cunard after Boris Becker was forced to retire from their match while trailing 6-2, 3-0.

The German started well enough, holding his opening service game, but later in the set, as he ran for a ball, he strained his hamstring.

Becker had treatment for the injury, but couldn't loosen up enough to continue.

After his thrilling victory over Richard Krajicek the previous night, Becker will now have to hope that McEnroe beats the Dutchman to send him through to Friday?s quarterfinals.

"With a day's rest I feel I could get back in shape," said Becker, who now needs McEnroe to beat Krajicek on Thursday to reach Friday's quarterfinals.

"I don't think it's a muscle pull so in 48 hours it could get better and heal. But, if Krajicek wins, I'm out regardless, so I have to look to my old friend John to take care of business and give me a chance!"

McEnroe was pleased to win through to the last eight, but disappointed that he couldn't finish the match in the traditional way.

"It's too bad because you look forward to matches like that. The good news is that I didn't have to put out too much," said McEnroe.

At 45, he is the oldest man in the draw, but he looked in tip-top condition as he sought to end the 2004 Delta Tour of Champions season on a high note.

"I haven't played as much this year but I still try to keep fit and train. When I walk out on a court I am still very serious about playing and competing - I don't see any point in going out there if you are not going to try to win."