At the US open semi-finals, Serena Williams loses her cool - and the match.

After a line judge calls a foot fault, Serena lost her temper and shouted at the judge. That led to a penalty point for Williams' opponent Kim Clijsters, which resulted in a loss for Williams.

She was fined $10,500 and has issued an apology. Meanwhile, the video of her outburst is gaining momentum online.