Serena: I'm the best

Serena Williams marched into the second round of the US Open on Tuesday and despite being seeded only fourth at Flushing Meadows, the American is in no doubt she is the world's best player.

"Of course I believe that," said Williams after powering to a 6-1, 6-1 win over Coco Vandeweghe after less than an hour on court. "I think there's a number of players on this tour, a few players who believe that.

"I don't care about the ranking. I've been No 1. It's cool. But my thing is just to be the best player. If that means I'm winning and I'm not number one, that's fine."