World number one Caroline Wozniacki began life at the top with an injury scare on Friday, while Ivan Ljubicic completed a cull of seeds when he beat Andy Murray on yet another smoggy day at the China Open. Second seed Murray joined Robin Soderling (third) and Nikolay Davydenko (fourth) on the scrapheap after being thumped 6-3 6-2 by Croatia's Ljubicic in the quarter-finals.
Ecstasy turned to agony for Wozniacki less than 24 hours after she was crowned world number one when she crumpled to the ground clutching her left knee in tears while leading Serbia's Ana Ivanovic 7-6 3-1. The 20-year-old overstretched as she smashed a backhanded return but after taking an injury time out to get her knee strapped, she showed her champion's instinct to reach the semi-finals by shunting aside Ivanovic 7-6 6-4.
"I felt pain when I jumped down on my knee. Not very nice thoughts went through my mind," Wozniacki told reporters. Air quality was so bad at the Olympic tennis centre for the third day running that top seed and champion Novak Djokovic offered a solution to the problem.
"A box of oxygen or something on the bench would be great, but we don't have it. I guess I will have to get used to it," he said after securing a semi-final place with a 6-3 6-2 win over Frenchman Gilles Simon. Soderling was beaten 6-2 6-4 by Spain's David Ferrer and Davydenko handed a 7-6 6-4 defeat by lofty American John Isner. Unseeded Isner now faces Djokovic.