By Piers Newbery BBC Sport at Wimbledon

Roddick has lost only one set on his way to the Wimbledon semi-finals

Andy Roddick faces the toughest test of his credentials as Wimbledon favourite when he takes on Roger Federer in the semi-finals on Friday.

The fifth seed has been in superb form over the last month, winning Queen's before sweeping through the first five matches at Wimbledon for the loss of just one set.

"I haven't beaten (Federer) yet but I think we both have an air of confidence right now," said Roddick.

"I'm going to try and take care of my serve and look for breaks when I can."

It's a match that everyone's been waiting for Roger Federer

The seedings would suggest that Federer, number four, is the favourite, and the Swiss star has also dropped just a single set so far.

But it is a mark of how Federer has underachieved so far in his career that this will be his first Grand Slam semi-final.

"I've been waiting a long time for this moment," said Federer.

"People have been talking for a long time about me taking the next step. Now I'll try to go further.

"It's a match that everyone's been waiting for. I've managed to return his serve in the past and I'm not worried."

Head to heads: Men's semi-finals

The 21-year-old Federer may be the closest any player gets to a new Pete Sampras in terms of style, but he has been helped enormously by a favourable draw over the last 10 days.

Roddick, on the other hand, has beaten Greg Rusedski, Paradorn Srichaphan and Jonas Bjorkman, and with his huge serve working well he will be hard to stop.