Yuki Bhambri braved cramps to get the better of Ireland's John Morrissey and enter the semi-finals in the boys' singles of the tennis event at the inaugural Youth Olympics in Singapore on Wednesday.
The sixth seed Indian defeated Morrissey 6-4, 6-4 in the quarter-finals at Kallang Tennis Centre.
"It was an up and down match, and the momentum kept shifting. Every match is going to be tough now," Yuki said.
The 2009 junior Australian Open champion will next face second seed Damir Dzumhur, who beat seventh seed Hungarian Mate Zsiga 6-3, 6-4 in his last-eight stage match.
Dzumhur, who is from Bosnia & Herzegovina, fought back from a break down in the second set against his Hungarian opponent, who was struggling on court with heat illness.
"It was a tough match, but my best match so far. When I saw that my opponent was unwell, I knew I had to keep playing the same way I had been," Dzumhur said.
The other semi-final will be between unseeded Victor Baluda of Russia and Colombian Juan Sebastian Gomez, both of whom toppled seeded players in their quarter-final matches.
Baluda overcame third seed Tiago Fernandes of Brazil 6-2, 7-6(5) while Gomez ended the run of Britain's Oliver Golding 6-4, 6-0.