Andy Roddick expects Rafael Nadal to defend his Wimbledon title even though the Spaniard is injured.

Roddick moved into the third round of the AEGON Championships with an easy, straight-sets win over Kristof Vliegen on the day Nadal confirmed he would be doing all he could to shake off his troublesome knee problems in time for the start of Wimbledon.

Nadal pulled out of the AEGON Championships at the Queen's Club to concentrate on getting fit in time to defend his title at SW19.

"I have been playing with pain on my knees for some months now and I simply can't go on like this," said Nadal in a statement today. "The pain was limiting certain movements in my body, which affected me mentally as well.

"After the tests, and with the appropriate treatment, we have decided to travel to London next Tuesday.

"I am going to give my 200% to be ready for the most important tournament in the world. The tournament that I always dream about.

"I will not go out and play, especially on the Wimbledon Centre Court, if I am not 100% ready to play."

But Roddick, a two-time Wimbledon runner-up, believes the Spaniard will be at SW19.

The American also admitted he has been playing with tendinitis for much of his career.

"I've had tendinitis for years," said Roddick. "It's uncomfortable and it's painful but, on a positive side for Rafa, it's not something that's going to be a career-threatening injury if you play on it.

"It's kind of a fancy term for overuse. I don't think that, in my mind, I ever thought that his Wimbledon defence was in jeopardy.

"Rafa has had knee tendinitis for a long time and he's won grand slams while he's had it.

"I'm certainly not going to underestimate Rafa. I think he's going to be there. I think he's going to be fine and I think he's going to put forth all the effort he has. He's certainly proven that in the past."

But Roddick, who went into last year's Wimbledon competition with a shoulder problem, warned Nadal carrying a nagging injury does have a severe effect on your confidence.

"If you don't know whether you're going to play or not, you probably shouldn't," said Roddick.

"It was pretty frustrating last year knowing that I was only able to hit so many serves a day.

"I felt I was going onto the court hoping as opposed to expecting. That's a tough thing.

"At Wimbledon last year, when push came to shove and I had to produce, I didn't. I hadn't had the practice. "A lot of the time it's not battling through the actual pain of the injury, it's not being able to get the practice in that you need to go out there and do it."

Elsewhere at the AEGON Championships, Juan Carlos Ferrero progressed into the second round with victory over former tournament runner-up Sebastien Grosjean - his 400th career win.

Wild card Grosjean lost the first set 6-2 and was then forced to retire with the score at 2-1 in favour of Ferrero in the second set.

It was Grosjean's first ATP tournament since October but the player's troublesome right shoulder injury forced him out of action again.

The tournament's number 13 seed, Ernests Gulbis, crashed out to Alberto Martin of Spain 7-6 (11/9) 6-4.

But America's James Blake made it through to the third round with a straight-sets success over big-serving Croat Ivan Ljubicic.

The sixth seed, whose mother Betty is English, won the first set 6-2 before finishing off the Croat's challenge with a 7-6 (7/4) tie-break triumph.