Another year, another Wimbledon. But will Roger Federer be able to make it a record sixth straight win at the Grand Slam in the face of perhaps his greatest opposition ever?

The Swiss master has won his last 60 matches on grass and has not lost a single match at Wimbledon since claiming the title for the first time in 2003. A win this year would make history for Federer, passing Bjorn Borg's record five straight Wimbledon wins. Why, then, does it seem that Federer is perhaps at his greatest risk ever of losing the prestigious crown this year?

The obvious answer is, of course, Rafael Nadal. After humbling Federer at the French Open final last month, Nadal then went on to claim his first ever grass title only a week later, downing both Novak Djokovic and Andy Roddick in straight sets in the process.

In his last 29 matches, Nadal has only lost a single match and it seems that the Spaniard is only getting better and better every single year and on every single surface. Now, more than ever, it looks like Nadal could be the first man, again since Bjorn Borg, to win both the French Open and Wimbledon titles in the same year.

Federer, on the other hand, seems to have lost some of his aura of brilliance and has yet to claim a Grand Slam title this year – something that has not happened since he began his reign over men's tennis in 2003.

The next contender after Nadal would certainly have to be Djokovic. After a brilliant beginning to 2008, including the Australian Open title, the Serb looks both ready and able to truly make his mark on the men's circuit. Djokovic has landed in Federer's side of the draw and we are set to witness possibly their most spectacular encounter ever in the semi-finals.

Djokovic's supreme talent is inarguable; it seems that the only thing holding him back is his ability to remain consistent in the face of great pressure. If he can get a handle on his nerves in the big moments, then we may very well see a final without Roger Federer this year.

Apart from these two major threats to Federer's dominance, there are certainly others be considered. Andy Murray, the British No. 1, has caught the eye of many veteran tennis stars in recent weeks. John McEnroe and Bjorn Borg both think Murray has what it takes to win a Grand Slam in the future, and certainly to progress further than his current best fourth-round performances.

Even Murray himself believes that he finally has the ability to really give the big names a challenge. “I can do it. I haven’t felt any extra pressure this week,” said Murray of his Wimbledon chances.

With many new stars rising to take Federer's place at the top of the ATP rankings, it is no wonder that Federer looks at his most vulnerable ever to drop the Wimbledon crown. But what does the World No. 1 himself think of his chances? "I'm still the big favourite," said Federer.

Only two Grand Slam wins away from equalling Pete Sampras's record 14 title wins, the former tennis great himself still thinks that the 26-year-old Swiss star is perfectly capable of continuing his winning run, in spite of recent results.

''As great as Roger is, he's going to have his losses and his bad days. It's human nature to go through some lulls,'' Sampras said. ''The media needs a story and something to grab on to, like he's lost his edge. He hasn't lost his edge."

Even when in top form at Wimbledon 2007, it took Federer a marathon five sets to overcome Nadal in the final. This year, with Nadal better than ever and perhaps Federer the weakest he has been for years, it will be no easy ride for Federer no matter who he faces in the final.

With so many talented players confident of their chances at this year's Wimbledon, prepare to witness perhaps the greatest Grand Slam that we have seen in many, many years.

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