Konta was facing set point in the second set against Tsvetana Pironkova in her 2nd round of the U.S open 2016 women’s singles when she collapsed.
The 13th seed led Bulgaria’s Tsvetana Pironkova 6-2 5-6 at Flushing Meadows when she crouched down to her knees and appeared to be hyperventilating.
Konta was facing set point after an hour and a half in hot and humid conditions, and with Pironkova an increasing threat, when she bent over, stooped to her knees and then rolled on to her back.
The Briton took a medical timeout before returning to court for long enough to send a second serve long and drop the set prompting a lengthy visit to the locker room.
The Briton, 25, who took a lengthy break, recovered to win 6-2 5-7 6-2.
Konta followed compatriot Kyle Edmund on to court 13, with the Yorkshireman also through to the third round after a 7-5 6-4 6-4 win over American wild card Ernesto Escobed
Konta is seeded at a career-high 13th and looked every inch the world-class player as she dominated the early stages, but the contest took a dramatic twist late in the second set.
She will play Swiss 24th seed Belinda Bencic in the third round on Friday.
Miles Maclagan, British tennis coach in a statement said, “We can’t really over-exaggerate the scenes we saw, on her hands and knees, heart racing and struggling for breath, an amazing effort from Jo Konta”.
“Maybe we shouldn’t be surprised, she’s got herself to the edge of the top 10 and you don’t do that without a little bit of steel in your spine. We saw that today.” He added