Jack Sock faints during U.S. Open match, forced to retire

American tennis player Jack Sock fainted on-court Thursday at the U.S. Open and was forced to retire from the tournament.

American tennis player Jack Sock fainted on-court Thursday at the U.S. Open and was forced to retire from the tournament.

Sock was leading Ruben Bemelmans in the second round of the men's bracket two sets to one when he passed out. He received treatment immediately and had to be helped off the court due to heat exhaustion and cramping. Sock was drained to the point where he was unable to shake Bemelmans's hand.

It's been a humid week in New York City, where temperatures hit 93 degrees Fahrenheit on Thursday and where the conditions have been unforgiving for Open contestants. On Wednesday, Australian Thanasi Kokkinakis was forced to retire two games into the fifth set of a match he led after severe dehydration and muscle cramps. Marina Erakovic of New Zealand retired three games into the second set of her match against Simona Halep.

• U.S. Open 2015: Day 4 matches to watch

Jack Sock had to retire. You'd be surprised at how quickly heat exhaustion occurs, esp the disorientation. Stinks pic.twitter.com/dj9cNmyXIR

— Prim Siripipat (@prim_siripipat) September 3, 2015

Jack Sock had to retire because he folded while he was leading 2 sets to 1 on Bemelmans #USOpen (via @BenRotenberg) pic.twitter.com/6M8xDqzfHj

— We Are Tennis (@WeAreTennis) September 3, 2015

- Jeremy Woo