The six-time US Open champion Serena Williams of the United States began her pursuit of a record-equalling 24th Grand Slam singles title with a dominant 7-5 6-3 win over compatriot 96th-ranked Kristie Ahn.
The 38-year-old went a break down in both sets but recovered to win in an hour and a half as she chases Margaret Court’s Grand Slam tally.
Williams gathered momentum late on, winning four straight games against world number 96 in the second set.
But she will not be joined in the next round by two-time US Open champion sister Venus Williams, who lost 6-3 7-5 to Czech 20th seed Karolina Muchova.
An error-strewn performance meant that seven-time Grand Slam champion Venus, 40, made her first-ever opening-round exit at the US Open.
Meanwhile, men’s No. 2 seed Dominic Thiem advanced, having been leading 7-6 (8-6) 6-3 when Spanish opponent Jaume Munar retired from the match.
Thiem, 26, will face Indian world number 124 Sumit Nagal in the second round as he looks to capitalise on the absence of Roger Federer and Rafael Nadal to win a maiden Grand Slam title.
Russian 3rd seed Daniil Medvedev is also through to the second round, comfortably beating Argentine Federico Delbonis in straight-sets 6-1 6-2 6-4. He will play Australia’s Chris O’Connell next.
Former world number one Kim Clijsters’ return to Grand Slam tennis ended in defeat as Ekaterina Alexandrova of Russia prevailed 3-6 7-5 6-1.
Belgium’s Clijsters – a three-time US Open champion – was given a wildcard for the tournament after coming out of retirement earlier this year.
Williams had to overcome some inconsistencies, gifting Ahn two breaks of serve, but brushed aside the suggestion that the lack of fans on Arthur Ashe Stadium had affected her level of play.