Bianca Andreescu, of Canada, returns a shot to Caroline Wozniacki, of Denmark, during round three of the US Open tennis championships Saturday, Aug. 31, 2019, in New York. (AP Photo/Eduardo Munoz Alvarez)

Canada's Bianca Andreescu defeated Denmark's Caroline Wozniacki 6-4, 6-4 on Saturday to reach the fourth round of the US Open.

The 19-year-old Ontarian won the first set in 40 minutes, then blew a 3-0 lead in the second before bouncing back and winning.

 It was the second match between Andreescu and Wozniacki this season. Andreescu beat the former No. 1 in the world in January in Auckland. The New Zealand win was the first career victory for Andreescu against a top-10 world player. She has since added six to her record.

This time, Andreescu was the favourite at the 15th seed, while Wozniacki has slipped to 19.

 Andreescu will face American Taylor Townsend next round. The American defeated Romania's Sorana Cirstea 7-5, 6-2.

The 116-seed Townsend surprised fourth seed Simona Halep earlier this week.