US tennis player Andy Roddick believes he can win a fifth title at Queen's Club and challenge for the Wimbledon title.

Roddick, who lifted the trophy at Queen's in 2003, 2004, 2005 and 2007, joins defending champion Rafael Nadal and Britain's Andy Murray in the field.

Roddick, who got married at the weekend, believes he stands his best chance yet of completing the grass court double after losing weight and adapting his game.

"I'm excited about my prospects this year," said Roddick, in a video interview on the AEGON Championships website.

"Last year I was going into Wimbledon a little under-prepared. I hadn't really played a whole lot (because of injury) and to be honest I haven't played my best tennis at Wimbledon over the last couple of years.

"This year I'm playing better and moving a little bit better so I'm really excited."

Roddick's form has improved under coach Larry Stefanki, who helped him reach the Australian Open semi-finals in January and is convinced Roddick can win Wimbledon.

"I think he's as capable as anyone to win on the grass, and I'm talking Wimbledon," he said.

"If he can serve with the variety that he's serving right now, put himself in a position to move into the court more, play on the baseline on the return of serve and attack a lot more, I think the window of opportunity is very big for him at Wimbledon."