It is becoming increasingly difficult to believe that the all-time great Roger Federer will win more than one more major, as it's been two and a half years now since he has raised a Grand Slam trophy and his two primary rivals -- Novak Djokovic and Rafael Nadal -- are in the primes of their careers.

But with his nemesis Nadal out of the Wimbledon draw, the Swiss has the best opportunity he's had since he grabbed the 2010 Australian Open (when an injured Nadal fell in the quarters to David Ferrer) to enter the winner's circle again. It is by no means a great chance, as he will face Djokovic in the semifinals, the same guy who has beaten him in six of the their seven past meetings. However, the match will be played on grass and the two have never faced off on the tour's fastest outdoor surface.

Federer is more comfortable in the cozy confines of Wimbledon's Centre Court than he is anywhere else, and somewhere deep in his arsenal he has the weapons to repel the relentless Serbian. But everything is going to have to come together for him in order for him to pull off the upset, and yes, even though he’s a six-time Wimbledon champion, it would be an upset. Djokovic staggered him time and time again at Roland Garros until delivering a heavy knockout punch and although that match was obviously played on clay, it was on neither man's best surface.

On hard courts, where both have shined, Djokovic has won their last four matches, including at the 2011 Australian and US Opens, even when Federer decided to try and be more aggressive and attack more. The Serbian's offense has improved immensely since 2010 and while he doesn’t look as pretty caressing drop shots or smoothing volleys, the defending Wimbledon champion is more solid from the backcourt, has a more dependable and forceful return of serve, and has actually become a very efficient volleyer having won 65 percent of his 135 net approaches during Wimbledon.

Any way you look at it, the Swiss has to show that he still has the will and the way to best Djokovic in three out of five sets.

Here's how German Florian Mayer, whom Djokovic took care of in three sets in the quarterfinals, looks at it: "It's a very open match. I think it's a good chance also for Roger maybe to reach world No. 1 if he can beat Novak. So he will be very motivated. But I think Roger also has to play on a really high level to have a chance to beat Novak."

It's not just a high level, Federer is also going to have to consistently mix things up and play the match on his terms, which does not mean getting consistently caught up in crosscourt rallies where the Serbian is able to pull him further and further off the court until he can pound a down the line winner. No, the 30-year-old has to deftly employ his slice backhand, try and chip and charge, pull Djokovic forward with drop shots, vary his first and second serves, and whenever he gets a ball into his forehand wheelhouse, take a big crack at it.

Federer says that 126 matches into his grass court career that he understands how the surface differs from others. While most of the players mention how the surface has slowed down over the past decade, it’s still a very quick, slick surface that favors directed, rapid-fire play.

"We're used to playing with much more topspin and giving ourselves margin over the net, but then also into the court at the back," he said. Whereas on grass I think it's worth it to go closer to the lines, use a lot of the down‑the‑line shots, which aren't easier to pull off on other surfaces.

It is obviously slowing down, but I still believe the aggressive player can be rewarded if he plays the right way."

Djokovic says that when he goes on court on Friday, he won't be thinking about 16-time Grand Slam champion Federer's amazing resume. He thinks he proved a lot last year by battering Jo-Wilfried Tsonga and Nadal for the title, and he has not been pushed in any of his first five matches during this fortnight. In fact, he has looked better than any of the semifinalists and the reason why he has been flying under the radar is because he is winning so easily and fans would rather take in dramatic contests than routine victories.

Moreover, he is trying to play even more aggressive than last year and has nailed 44 aces-- just three less than the so-called bigger server Federer.

"I don't think about his history or his success or whatever too much when I'm on the court,' Djokovic said. "I just want to win that match."

"Obviously I'm aware that Novak is the defending champion and the world No. 1,' Federer said. "That's not going to make it easy to come through. I know it's possible. I know I'm playing really well. I am aware things are going to get complicated in the next match.