Home favorite Coco Gauff overcame serving struggles to beat Australia's Ajla Tomljanovic 6-4 6-7 (2-7) 7-5 in a tough US Open opening match. The third seed, who played for nearly three hours, said, "It wasn't the best but I'm happy to get through." Gauff recently sacked coach Matt Daly and hired biomechanics expert Gavin MacMillan to fix her inconsistent serve. "It has been really tough – mentally exhausting – but I'm trying," Gauff admitted of her serve issues. World number two Iga Swiatek began her title bid with a dominant 6-1 6-2 win over Colombia's Emiliana Arango. Swiatek, fresh from her Wimbledon triumph, next faces Suzan Lamens of the Netherlands in the second round. Eighth seed Amanda Anisimova beat Australia’s Kim Birrell 6-3 6-2 despite 17 unforced errors in the first set. The American improved in the second set, winning five straight games to set up a second-round match with Maya Joint. Danielle Collins exited early for the second consecutive year, winning just two games in a loss to Romania's Jaqueline Cristian.