Tiafoe and Keys lead home charge into US Open third round
The home stalwarts flew the American flag during the day session at Arthur Ashe Stadium where Keys, the 14th seed, beat Australia's Maya Joint 6-4, 6-0 while Tiafoe was leading 6-4, 6-1, 1-0 when Kazakhstan's Alexander Shevchenko retired.
Tiafoe, who reached the New York semi-finals in 2022 and this year was a runner-up in his final tune-up event, was in complete control when Shevchenko, who had the trainer out after the second set, suddenly called it a day.
"Happy to get it done. Hate to win it that way but overall I thought I actually played pretty well today," Tiafoe said after a stress-free victory during which he changed shirts five times.
Tiafoe broke Shevchenko to take the first set and grabbed a 5-1 double-break lead in the second before serving out the one-sided match.
Keys, making her 13th main-draw appearance at the U.S. Open, struck first against Joint when she converted on her third break-point opportunity for a 4-3 lead en route to wrapping up the opening set on her serve.
The American opened the second with another break and sprinted to the finish line in 62 minutes.
"After the first set I feel like I made a few adjustments on my returns just to put a little bit more pressure on her," said Keys, who retired from her two previous tournaments at Wimbledon and Toronto.
"And I felt like once I was able to get a little bit out ahead I really just ran with the moment and was able to close it out really well."
Up next for Keys, who lost to fellow American Sloane Stephens in the 2017 US Open final, is a clash with 33rd-seeded Belgian Elise Mertens.
It was not all good news for the American contingent at Flushing Meadows as unseeded American Taylor Townsend fell 6-3 7-5 to Spanish 26th seed Paula Badosa.
Other players representing the stars and stripes in action on Wednesday include defending champion and third seed Coco Gauff, who will open the night session on Ashe versus unseeded German Tatjana Maria.
Ben Shelton, who electrified the home crowds last year with a spirited run to the semi-finals, is closing out the day session on Grandstand against Spain's Roberto Bautista Agut with the winner going on to face Tiafoe.
World number 12 Taylor Fritz, the highest-ranked American in the men's draw, will cap play in Louis Armstrong Stadium against Italy's Matteo Berrettini.