Serena Williams begins what is expected to be her final US Open with a match against Montenegro's Danka Kovinic but things could get tough quickly for the 23-time Grand Slam champion with second seed Anett Kontaveit possibly awaiting the winner.
The US Open draw released on Thursday did Serena no favours, the 40-year-old American landing in the bottom quarter where fifth-seeded Tunisian Ons Jabeur, the Wimbledon runner-up, 10th-seeded Russian Daria Kasatkina and last year's losing finalist Leylah Fernandez of Canada all lurk.
Serena signalled her intention to retire this month, saying she was "evolving away from tennis" but never confirming the US Open as her final event.
The tennis world, however, is preparing a massive retirement party at Flushing Meadows with fans hoping it will be a long one.
Serena starts her bid for a record-equalling 24th Grand Slam singles title on Monday against a player she has never faced before.
But the six-time US Open winner will be wary of the 80th-ranked Kovinic, who has enjoyed her best career Grand Slam results this year having reached the third round at the Australian and French Opens.
Top seed and world No.1 Iga Swiatek opens against Italy's Jasmine Paolini and headlines a top half of the draw including American hopes eighth seed Jessica Pegula and 2020 Australian Open winner Sofia Kenin along with major winners Garbine Muguruza, Jelena Ostapenko and Petra Kvitova.
Britain's Emma Raducanu, who captivated the tennis world last year at Flushing Meadows by going from qualifier to Grand Slam winner, will open her title defence against Alize Cornet.
The 19-year-old will have to be sharp against the French veteran who is contesting a record 64th consecutive Grand Slam event and reached the quarterfinals at this year's Australian Open and last 16 at Wimbledon where she ended Swiatek's 37-match win streak.
The marquee match of the first round could be between twice US Open champion Naomi Osaka and 19th-seeded American Danielle Collins, the Australian Open finalist.