Giant-killer Robson knocks out China's Li Na

China's ninth seed Li Na suffered the same fate as Kim Clijsters as she was dumped out of the US Open on Friday by British teenager Laura Robson.

The former French Open champion was outplayed by the 18-year-old, going down 6-4, 6-7, 6-2 in the third round.

"I was feeling that I still had a chance but I was making a lot of mistakes the whole match," Li told reporters. "That gave her a lot of confidence and gave her free points, made her feel like she could win."

Former Wimbledon junior champion Robson had sent three-time champion Clijsters into retirement in round two and followed up with another nerveless display full of strong serving and huge hitting, especially on her forehand.

Li lifted her game to snatch the tiebreak 7-5 and force a decider but Robson continued to attack at every opportunity.

At 2-2 in the third set, Robson thought she had broken serve but umpire Louise Engzell ruled that the point should be replayed, even though Li had missed with her reply.

But Robson kept her head, breaking twice to lead 5-2 and then serving out the match to set up a meeting with defending champion Samantha Stosur.

"I knew if I kept sticking with her and playing my shots it might pay off and it did," Robson said in a television interview.

"I had a few break points early on and I gave them up with average returning, so when I got a chance I knew I had to go for it.

"She's a great hitter so knew I had to go for it. I'm going to go back to the gym and try to recover for the next match."

Photograph: Jay Mandal