Clijsters aims to serve up semi-final cracker

Kim Clijsters will attempt to oust a second Williams sister from the US Open as she bids to prolong her remarkable run at Flushing Meadows in a mouthwatering final-four clash tonight. Her surprising revival, which saw her beat 18th seed Lin Na in the quarter-finals, has shocked even Clijsters herself. The Belgian 28-year-old is playing off a wildcard in her third tournament of the season having retired from tennis after defeat to Maria Sharapova in the 2007 Australian Open.

"I never had the mentality before the tournament that I would get to a semi-final or final at the grand slams," she said. "I definitely didn't have that idea but something switched with me after Toronto [her second tournament back] where I felt 'OK, I can compete with these girls', because that was obviously a big question in my mind. "Although I was hitting the balls really good in practice and I felt physically I was doing well. You still want to know what it's like to play against those girls and get a feel for how the level has changed. That was something I didn't know, so I am surprised that I'm sitting here right now but I'm very happy."

Clijsters dispatched China's Na comfortable style 6-2, 6-4, setting up one of the most anticipated matches of the tournament so far. Having seen off the elder Williams sister Venus in a fourth round 6-0, 0-6, 6-4 thriller, Clijsters' will now have the chance to dethrone the younger sister, defending champion Serena. She will need to move up another gear when facing 2008 US Open champion Williams, who has made short work of progressing to the semis.

Having beaten Italy's Flavia Pennetta 6-4, 6-3 in their Tuesday night quarter-final, the American is looking forward to meeting Clijsters on court tonight. "She is such a great person and I only wish the best for her - though not in the next match of course," said Williams, "It will be a great match. She has nothing to lose and is having so much fun, which makes me so happy." "Initially I was surprised how well she's been doing but she did so well a couple of weeks ago that I knew she was someone to look out for."