Sloane Stephens resumes the defence of her U.S. Open crown against unseeded Ukrainian Anhelina Kalinina on Wednesday, but will also have to contend with stifling weather conditions that show few signs of easing.
The oppressive heat and humidity in New York prompted organisers to implement its heat policy to provide some relief for the players on Tuesday with temperatures predicted to inch up to 96 Fahrenheit (35.5 Celsius) on Wednesday.
With the roofs of both the Louis Armstrong and Arthur Ashe stadiums set to stay open, players on court for the morning session at Flushing Meadows will bear the brunt of the heatwave.
Briton Andy Murray, playing in his first Grand Slam since undergoing hip surgery, follows Stephens on Arthur Ashe, where he will take on Spanish veteran Fernando Verdasco for a place in the third round.
Over on Louis Armstrong, 16th seed Venus Williams is up against Italy's Camila Giorgi in the afternoon session, followed by 2009 champion and third seed Juan Martin del Potro.
The big-serving Argentine, a crowd favourite in New York, breezed through his first round encounter with American Donald Young in straight sets and will hope to turn in a similarly clinical performance against Young's compatriot Denis Kudla.
Swiss wildcard Stan Wawrinka, the 2016 champion, is first on Grandstand against France's Ugo Humbert, before 11th seed John Isner faces Chilean Nicolas Jarry.
Last year's runner up Kevin Anderson, who was pushed to five sets by American Ryan Harrison in an energy-sapping first round encounter, will find himself back on court 17 to take on Jeremy Chardy.
Anderson, who lost to Rafa Nadal in last year's final, looked to be hampered by a leg injury against Harrison but will take confidence from the ease with which he beat Chardy in straight sets at the Cincinnati Open this month.
The weather should ease slightly in the evening, with meteorologists predicting a 40 percent chance of scattered showers and thunderstorms developing.
Serena Williams is first out on Arthur Ashe for the evening session to face Germany's Carina Witthoeft before Nadal faces unseeded Vasek Pospisil.
Nadal progressed to round two after his good friend and fellow Spaniard David Ferrer retired with a calf injury on Monday and will need to find a way neutralise Canadian Pospisil's strong serve and powerful forehand.
