@CNN: Serena Williams drops a set at US Open but progresses to quarterfinals https://t.co/7p73kgd3lQ https://t.co/RcqRHYH9E2

@CNN: Serena Williams drops a set at US Open but progresses to quarterfinals https://t.co/7p73kgd3lQ https://t.co/RcqRHYH9E2