American qualifier Learner Tien shocked the tennis world on Thursday when he upset last year’s Australian Open runner-up Daniil Medvedev in a nearly five-hour, five-set match in the second round.

Tien took an early two-set lead (6–3, 7–6) before dropping the next two sets to Medvedev (6–7, 1–6). The final set went into a tiebreak, with the 19-year-old capturing a 10–7 win in the tiebreak. The match lasted four hours and 49 minutes into the early hours of Friday morning in Melbourne at Margaret Court Arena.

“I was definitely hoping it wouldn’t go to a fifth-set ‘breaker. … It was definitely harder than maybe it could have been, but, whatever,” Tien said. “I really appreciate all you guys staying out here. I know it’s late. I have no idea what time it is.”

The California native is the youngest player to reach the third round of the Australian Open since Pete Sampras in 1990. He will face Frenchman Corentin Moutet in the third round.

Tien isn’t the first teenage phenom to upset a top-10 ranked player at this year’s Australian Open as No. 6 Casper Ruud lost to 19-year-old Jakub Menšík and No. 9 Andrey Rublev lost to 18-year-old João Fonseca. Tien’s five-set thriller definitely has stood out in the tournament thus far.

Maybe it’s the year for a teen phenom to make their mark in the tennis world.