Cramp has cruelled Canberra teen Nick Kyrgios' hopes of winning a wildcard into next month's Australian Open tennis tournament.
Playing in the quarter-finals of the wildcard play-off at Melbourne Park on Wednesday the 17-year-old was leading No.8 seed Matthew Barton 4-0 in the fifth set when the stifling heat started to take its toll.
After already winning the Australian under 18 boys title on Sunday, Kyrgios had three break points to go to a 5-0 lead in the decider when he started to cramp.
He dropped the next game and then couldn't manage to sit down between games due to a full body cramp.
The AIS product, who has a ripper forehand, called for a trainer and tried to play on but agonisingly he wasn't able to serve with any pressure and was ultimately assisted from the court.
The match finished in Barton's favour 7-6 (7-3) 3-6 6-3 6-7 (7-5) 3-4 when Kyrgios retired.
This is the first year that qualifying has been played over five sets throughout, with every match bar the final a three-set affair previously.
But this year organisers decided to emulate grand slam conditions.
Ranked No.4 in the world in the under 18s, Kyrgios, who lost the US Open boys doubles this year, has a bright future.
He eliminated wildcard top seed Sam Groth in four sets on Monday.
One player who hardly felt the heat was second seed JP Smith.
A Townsville product, Smith eliminated seventh seed Greg Jones in their quarter final.
Smith has spent the past four years on a tennis scholarship at the University of Tennessee in the US, where he also gained a Bachelor of Economics and Business Administration.
He's playing his first full year on tour and overcame Jones 6-4 3-6 7-6 (8-6) 6-4.
"The heat was fine, the sun was more of an issue for me but I managed to pull it out," 23-year-old Smith said.
The women's quarter finals will take place on Thursday with rising star Ashleigh Barty in action.