Gauff's serve remodel loomed over her tournament. It might be her forehand, which Naomi Osaka broke down to beat her, that matters more.

American Coco Gauff puts her serving issues behind her as she beats Magdalena Frech in straight sets to reach the US Open fourth round.

Coco Gauff produced her sharpest display of the week, brushing aside Magdalena Frech 6-3, 6-1 to reach the US Open’s last 16 in commanding style