New Delhi, Oct. 7 -- Pranav Karthik, the 21-year-old from Tamil Nadu, caused a major upset on Wednesday at the 31st Fenesta Open National Tennis Championship, rallying from a set down to defeat No. 4 seed Udit Kamboj in the second round.

Kamboj won the first set 6-1 and was neck-and-neck with his younger rival in the second set, which went to a tiebreak. Karthik won the tiebreak 7-3 and carried that momentum into the decider to win 1-6, 7-6 (7-3), 6-2 in 2 hours and 31 minutes, according to a press release from Fenesta Open.

"To be honest, I was thinking I was going to lose for sure after the horrible first set," Karthik said after the win. "I just kept serving well and maintaining my service games. And when it came to the tiebreak, it ...