Switzerland's Stan Wawrinka reached the fourth round of the US Open tennis tournament by walkover on Saturday when Slovenian Blaz Kavcic withdrew from their third-round match with a right foot injury.

Australian Open champion Wawrinka, the third seed who broke through for his first Grand Slam title in Melbourne in January, next faces 16th-seeded Spaniard Tommy Robredo.


Earlier on Friday second seed and five-time champion Roger Federer reached the US Open third round with a 6-4, 6-4, 6-4 win over big-serving Australian Sam Groth.
   

Federer took his night session record to 24-1 with the win that gave him a clash with Spain's Marcel Granollers on Sunday for a place in the last-16.

The game was interrupted by heavy rain in the first set with Grenollers leading 5-2.