|Venue: Flushing Meadows, New York Dates: 29 August-11 September|
|Coverage: Live radio commentary on Radio 5 live sports extra from 22:00 BST plus live text coverage on selected matches on the BBC Sport website.|
Britain's Johanna Konta reached the US Open third round - despite collapsing on court with blurred vision, breathing issues and an increased heart rate.
The 13th seed led Bulgaria's Tsvetana Pironkova 6-2 5-6 at Flushing Meadows when she crouched down to her knees and began hyperventilating.
Medical help arrived after several minutes and Konta, 25, took a lengthy break before winning 6-2 5-7 6-2.
"My heart rate spiked and I couldn't really control my breathing," she said.
"It was basically very embarrassing. I started hyperventilating. I started shaking. That's why I went down on the ground, because I was quite violently shaking."
Konta followed compatriot Kyle Edmund on to court 13 after the Yorkshireman had reached round three by beating American wildcard Ernesto Escobedo.
I definitely hit one of my limits - Konta
Konta is seeded at a career-high 13th and looked every inch the world-class player until the contest took a dramatic twist late in the second set.
After an hour and a half in hot and humid conditions - and with Pironkova an increasing threat - Konta was facing set point when she bent over at the back of the court and then rolled on to her back.
After lying on a towel and using ice bags brought over by the umpire, Konta waited for the doctor before making it back to her chair and telling the physio: "It felt like my whole body was going into shock."
She took a medical timeout before returning for long enough to send a second serve long and drop the set, prompting a lengthy visit to the locker room.
It appeared questionable whether she would return at all, but Konta returned and took control with an early break and took the final set in 50 minutes.
"We push our bodies to the limits that they can go," added Konta. "I definitely hit one of my limits. That was the way my body reacted.
"I was feeling a little bit the conditions and also my own energy levels. I was just managing the best that I could with what I had today."
She will play Swiss 24th seed Belinda Bencic in the third round on Friday.
The match stopped for too long - Pironkova
Pironkova, 28, was sympathetic towards Konta but felt her rhythm was unduly disrupted when the Briton took a second timeout to go to the bathroom.
"I wish I could say all players use bathroom breaks accordingly to go to the toilet," said the Bulgarian, ranked 71st.
"Some players use them to refocus. I don't think they should be used that way."
She added: "With that toilet break, I think the match was stopped for just too long. I had my momentum going, I was getting back in the match."
Russell Fuller, BBC tennis correspondent: "Konta was in some distress as - with no warning - she fell to the court, struggling for breath.
"When the match resumed, Pironkova completely lost her rhythm. The Bulgarian deserves sympathy for the length of time she had to wait, but there is no denying Konta played a magnificently canny final set. She used less pace, but great placement. Her shot selection was remarkable."
Miles Maclagan, British tennis coach: "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."