Going head-to-head with sister Venus for the 30th time brought out the best in Serena Williams as she hit top form at the US Open. Serena raced to a 6-1, 6-2 victory, equalling the most one-sided match in their long history.

She will next face Estonia's Kaia Kanepi. "It's not easy," said Serena, 36. "She's my best friend, she means the world to me and she's so supportive of my career and I'm extremely supportive of her career. Every time she loses I feel like I lose. I love her with all my heart and she's the only reason I'm still out here. I owe everything to her."