Coco Gauff overcame a year-long crisis with her serve to beat Turkey's Zeynep Sonmez 6-3 6-4 in the first round of the US Open, with her once-troubled shot now proving a key strength. The 22-year-old American, who suffered from serving yips last year that undermined her game and led to a fourth-round exit at Flushing Meadows, has rebuilt her technique with biomechanics expert Gavin MacMillan, who previously helped Aryna Sabalenka overcome similar issues.

Gauff, seeded fourth this year, opened with a swift love hold and dominated the first set, winning 93% of points behind her first serve. She fought off break points in the second set with a mix of aces and unreturned serves reaching close to 120mph, before closing out the match with three unreturned first serves to seal victory. Despite having hit the most double faults of any player on the WTA Tour this season (301), her average of 5.6 per match is lower than many rivals, and improved accuracy helped her win the Cincinnati Open title earlier this month. She will next face Spain's Paula Badosa.