NEW YORK: Unseeded Kim Clijsters's improbable charge into the US Open semifinals has surprised the Belgian as much as anyone.

Clijsters, who returned to the tour several weeks ago after two years on the sidelines, breezed by China's Li Na 6-2, 6-4 on Tuesday on Arthur Ashe Stadium.

"I never had that kind of mentality before the tournament knowing that I was going to get to a semifinal or final at the Grand Slams, obviously," said the 2005 Open champion.