Gauff defeats Siegemund to advance into US Open second round
Sixth seed Gauff, seen as one of the favourites for the title after recent tournament wins in Washington and Cincinnati, came from behind to win 3-6, 6-2, 6-4 in an attritional 2hr 50min tussle on the Arthur Ashe Stadium.
An ill-tempered match saw Gauff lose her cool with chair umpire Marijana Veljovic in the deciding set, with the 19-year-old accusing the official of failing to enforce time violation rules against Siegemund.
"I don't care what she's doing on her serve but on my serve she has to be ready," Gauff yelled at the umpire. "She's never ready."
Tempers then flared again when Siegemund was called for a time violation for the second time at 40-0 down, handing Gauff a 5-1 lead.
Siegemund remonstrated angrily with umpire Veljovic but to no avail.
The 35-year-old Siegemund, ranked 121 in the world, had frustrated Gauff with a superb performance to take the opening set, mixing her play cleverly and attacking the net behind a consistent serve.
The second set began with a remarkable 25-minute game that saw Gauff finally score her first break of the match, converting the eighth break point of the game.
The American then pulled away to win the second set convincingly before racing into a 5-1 lead in the third set.
Siegemund bravely dug deep to claw it back to 5-4 but Gauff held serve to clinch a second round duel with 16-year-old Russian Mirra Andreeva.