World number one Serena Williams swept past good friend Caroline Wozniacki of Denmark 6-3,6-3 in the US Open final to win her 18th grand slam title. Williams sailed through the tournament without dropping a set, finishing off Wozniacki in a snappy 75 minutes. "It was a pleasure for me to win my first grand slam here, and then this is number 18. I am really emotional," Williams told the packed Arthur Ashe Stadium. Wozniacki, the 10th seed, was in her first grand slam final in five years. Williams pocketed the $3m winner's purse along a $1m bonus for winning the US series.