LONDON (AFP) - Rod Laver praised Roger Federer on Sunday as the Swiss star aimed at surpassing Pete Sampras 's record of 14 Grand Slam titles, but admitted the American would come out on top in grasscourt rivalry. Australian legend Laver , the only man to win two calendar Grand Slams in 1962 and 1969, is a long-time admirer of Federer who will be chasing a sixth Wimbledon title when he meets Andy Roddick later in the day. But he believes that if the two had the opportunity to meet on a regular basis at the All England Club, seven-time champion Sampras would have the edge. "I think I might take Sampras , only because of his serve," said the 71-year-old. "He's got a big serve and volleying ability. He's a little more versatile when it comes to the power game. "Roger could certainly get the ball at his feet. But to return a big serve like that, not many players are used to a person serving that hard and getting in close to the net and volleying with success." Although Federer defeated Sampras in five sets here in 2001, it was the only time the two played with the Swiss star just starting to make his way at 19 while Sampras was already 28 and would play just one more Wimbledon. Laver described Federer 's assault on a record 15th major as "unbelievable". "You've got to be in the game and enjoy the sport to be able to do something like this. You're not going to make the 12 or 13 events if you don't respect the game and enjoy it," added Laver . "You almost think about table tennis when you start thinking about the way Roger plays with the racquet. But I think watching Roger, I think the public should just watch his feet, just watch him and not the ball, and you'd see how great a player he is to pull off some of the shots. "When he's half-volleying winners off the baseline you just marvel at his ability to do that." Laver believes it's impossible to describe Federer , or any other player, as the greatest ever, claiming that different eras and developments in equipment and fitness levels make such comparisons meaningless."I've always thought that you're the best in your era. That to me is a pretty good compliment," he said. But how would Laver match-up against Federer ."It's a different world, a wooden racquet against a composite racquet. The whole structure of the game has changed. It's a different speed. "Today when kids start off at age eight with this composite racquet, they've got spin and control within a couple of years. My coach, Charlie Hollis, said it's going to take you two years to perfect a forehand, two years for a backhand, two years for a serve."But today the players can perfect all this in six months." As far as Sunday's final is concerned, Laver leans towards Federer . "I'd have to say that Roger is certainly favoured to win the tournament," he said. "But if Roddick serves well, he could give Roger all he wants. And he has been serving well. Once his serve's working well, the rest of his game is working well. "But Roger plays a lot of individual shots and can break down a player when you're in a final like that because there's a lot of pressure out there."