India, Aug. 27 -- From the edge of the baseline on her forehand side, Coco Gauff sprinted the width of the court to the left. The crosscourt return came spinning and stayed low on the bounce. Gauff had to lunge to get there, slightly off-balance, but she connected sweetly with a two-handed backhand. The down-the-line winner was well celebrated in the Arthur Ashe Stadium by Gauff and the partisan American crowd.

With that winner, she overcame the tough challenge posed by Australia's Ajla Tomljanovic, sealing the first round of the US Open 6-4, 6-7 (2), 7-5 on Tuesday.

In many ways, the match point represented all the strengths and weaknesses in Gauff's game.

The first serve clocked 105 mph (169 kph) on the speedometer. It was a body ser...