Li Na has claimed that she was partly to blame for her shock defeat to Laura Robson in the third round of the US Open on Friday.

The ninth seed and former French Open champion was downed in three sets by the 18-year-old Brit inside the Louis Armstrong Stadium.

"She has a huge first serve, but it's not like I didn't have a chance" Li told reporters. "I was making a lot of mistakes in the whole match, so I gave her a lot of free points. That made her like, 'Oh, I've got more confidence. Oh, I can beat her.'"

Robson's reward for beating Li is a last-16 clash with defending champion Samantha Stosur.