PARIS (REUTERS) - World number three Stan Wawrinka cruised into the French Open fourth round against an out-of-sorts Fabio Fognini on Saturday (June 3), winning 7-6(2) 6-0 6-2 as the Italian's game fell apart after a strong first set.

The 2015 champion in Paris has yet to drop a set in the 2017 tournament, but this time he came close to conceding the first, which the unpredictable Italian failed to serve out before losing in a one-sided tiebreak.

Fognini, seeded 28, had won two of his three matches against top-five opponents this year, beating then fourth-ranked Kei Nishikori in Miami and number one Andy Murray in Rome.

But on a murky Court Suzanne Lenglen where the weather matched his own darkening mood, the Italian lost the second set without taking a game, punctuating wild forehands with a clutch of double faults before getting treatment on his left knee.

At 5-2 down in the third set, Fognini saved two match points before the 32-year-old Swiss fired down an unreturnable serve on the third.

"It was a very good first set and I was a bit hesitant, but after that I relaxed," Wawrinka said courtside.

"I am playing very well at the moment but we all know how that can go in a grand slam... Each game gets more difficult."

Wawrinka will play the winner of the all-French clash between Gael Monfils and Richard Gasquet in the fourth round.