Defending champion Roger Federer gave another tennis masterclass on Wednesday to reach the semi-finals once again.

If anyone could give him a game it was the big-serving Mario Ancic, according to the pundits, but Federer dismissed his challenge with ease, winning 6-4 6-4 6-4 on Centre Court.

Ancic was the last man to beat Federer on grass - here back in 2002 - but he never looked likely to repeat that win.

The Swiss maestro was in stunning form and only two rain delays prevented Ancic from suffering a rapid defeat.

The only point Federer struggled was when his concentration appeared to slip in the third set when he was already a double break up.

Ancic retrieved one break and had a break point in the next Federer service game, but the champion slammed the door shut and went on to complete victory.

Even the Swiss himself was impressed, saying: "It was an incredible performance. If I can keep this performance I don't see myself losing.

"You get to feel that you're absolutely in control. You're not afraid to try anything, you're not afraid to hit the ball hard, you're not afraid to go for aces.

"That's the sensation you get when you're playing so well. That's exactly what I felt."

Ancic was also impressed by the manner of Federer's win.

"I think he played unbelievably today,'' said the 22-year-old.

"We played in the quarters at the French Open but he was in much better shape today.

"I thought at times I played some good shots, that I did exactly what I had to do and that I was getting some winners from nowhere.

"I don't regret anything I did today and I think I was being aggressive but he was the better player.'

"At the moment I don't think anyone can beat him. I'd be very, very surprised.''

The day's big shock came late in the day when Marcos Baghdatis stunned former champion Lleyton Hewitt with a 6-1 5-7 7-6 6-2 victory.

Baghdatis dominated the early exchanges and won nine of the first 10 games against an out-of-sorts Hewitt.

However, the dogged Australian recovered to take the second set and at that point most fans would have expected him to progress.

Instead, Baghdatis won a tight third set on a tie-break and despite needing the attention of the trainer in the fourth wrapped up a famous win soon after.

The 18th seed said: "I went onto the court believing I could win because I have beaten a lot of good players but in the middle of the second I realised I was beating Hewitt. I started choking a little bit but I got through."

A disappointed Hewitt admitted: "It just didn't happen for me out there today. I struggled to get into the match and never played great. I just hung in there but was not able to take my chances."

The young Cypriot, a runner-up in this season's Australian Open, will have to wait to discover his semi-final opponent.

It will be either Rafael Nadal or Jarkko Nieminen but their clash was postponed until Thursday.

That was down to a combination of earlier rain days and the four-hour first match on Court One.

That proved to be a thiller with Jonas Bjorkman coming from match point down to beat Radek Stepanek.

The 34-year-old Swede, who is still in both the men's and mixed doubles too, proved his fitness is still immense by out-lasting the Czech, winning 7-6 (7-3) 4-6 6-7 (5-7) 7-6 (9-7) 6-4 in a match lasting three minutes over four hours.

A tearful Bjorkman admitted he had feared his chance of reaching another Grand Slam semi-final had passed him by.

He said: "I never believed I could get to the semi-finals of a major tournament again. Sorry, I'm very emotional.

"To be playing in a semi-final at 34 is a dream come true for me. I didn't believe I had any left in me.

"It's an unbelievable feeling and on court I just wanted to stay and hug everybody. I wanted to enjoy every moment out there.

"It was a tough match and you can never give up against an opponent like that."