Gauff had to overcome 23 double-faults to win for the first time since the French Open final, outlasting fellow American Danielle Collins 7-5, 4-6, 7-6 (2) in the second round of the National Bank Open.

Gauff's serve changes are still embedding into her tennis. But she has other ways to win when the double faults start.

Coco Gauff has suffered some recent surprising tournament losses, and she almost faced the same fate in the Canadian Open's second round.