NEW YORK (REUTERS) - Olympic champion Belinda Bencic put on a serving masterclass to beat Jessica Pegula 6-2 6-4 and reach the last 16 of the U.S. Open on Saturday (Sept 4).

The 11th-seeded Swiss won 85 per cent of her first serve points and smacked four aces to improve to a 3-0 record against Pegula, including a victory over the American at the Tokyo Games that kicked off her gold medal-winning campaign.

For Bencic, who has yet to drop a set in New York, the only struggle came when she was unable to convert three match point opportunities on Pegula's serve.

But Bencic held to love in the next game, firing an unreturnable serve to seal the win on a picture-perfect day at Louis Armstrong Stadium court.

Next up for Bencic is either Estonian Anett Kontaveit or Polish seventh seed Iga Swiatek, who play later on Saturday.