"Nadal hasn't really lost a claycourt match since I can't remember when, so nobody can beat Rafael Nadal on clay," the two-time Monte Carlo winner Wilander said.
"Federer does not have the good combination style game to play against Nadal, he does not suit him at all in fact. And you can see it much easier on clay that it's just a bad combination for Roger Federer."
Nadal, who has now won 63 consecutive matches on the surface after easing past Argentine Juan Ignacio Chela on Wednesday, is the twice-defending champion at the Monte Carlo Masters and the French Open.
Monte Carlo Masters
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22/04/2007 AT 17:17
The number two ranked Spaniard has beaten Switzerland's Federer six times and lost to him three times, including defeats in their previous two matches in last year's Wimbledon final and Masters Cup semi-final.
"Nadal is left-handed he is able to find Federer's backhand all the time in the serve and it's not a good mix," Wilander said.
"Apart from the fact, Rafael Nadal is one of those young guys who really is not afraid of anybody, it doesn't matter if his name is Roger Federer and he has won 10 majors or what, Nadal is just not afraid."
Despite his belief that Federer cannot beat the 20-year-old Mallorcan on clay, Sweden's Wilander says that the Swiss star is the favourite to complete his Grand Slam collection at Roland Garros this year, just so long as he doesn't face Nadal.
"I think on paper he might be the favourite actually, because I think he will be really focused on winning Roland Garros," Wilander said.
"He knows time is running out to win Roland Garros. He is not going to win it three times and I think he knows that. He's going to win it once, maybe twice, and I think this is the year to do it."
The 42-year-old Wilander, who like Nadal won his first French Open as a teenager, says that if Federer has to face a rematch of last year's final against Nadal, the Swiss star will fail.
"Is Rafael Nadal able to come through the draw again after winning clay court tournament after clay court tournament? That's the problem for Roger Federer," he said.
"If Nadal does not go through, Federer will win the French Open."
Follow complete LIVE coverage of the Monte Carlo Masters throughout the tournament on www.eurosport.com.
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