Kim Clijsters has revealed that although she was disappointed to lose in the US Open second round, she is happy with what she has achieved.

Clijsters, who lost to Britain's Laura Robson in the second round last night, has now officially retired from tennis and on reflection has admitted that she is pleased with the past two years.

"I think in the first hour after the match there was still disappointment and a little bit of frustration," Reuters quotes Clijsters as saying. "However after talking and thinking about the retirement, I'm happy.

"In the last year and a half or even two years, it's been kind of up and down and I'm happy that I stuck through it and was able to live a lot of these emotions that I've had. I'm kind of proud of myself that I was able to do that."

Clijsters won four Grand Slam singles titles in her career, including the US Open three times.