Carlos Alcaraz collapses to the court in delight after his record-breaking quarter-final victory over Jannik Sinner - AFP 

NEW YORK, AFP: Carlos Alcaraz battled past Jannik Sinner in five sets to reach the US Open semi-finals on Thursday in the latest ever finish in the tournament’s 141-year history.

A thrilling 5hr 15min duel that finished at 2:50 a.m. local time ended with the 19-year-old Alcaraz claiming a 6-3, 6-7 (7/9), 6-7 (0/7), 7-5, 6-3 victory to advance to a last-four showdown with Frances Tiafoe of the United States on Friday.

The previous record for the latest finish to a US Open match was 2:26 a.m., which had been set three times before.

Incredibly, it was the second early-hours-of-the-morning finish for Alcaraz this week.

The Spanish No.3 seed had edged past Croatia’s Marin Cilic in another five-set epic in the fourth round in a match that finished at 2:23 a.m. local time on Tuesday.

A crowd of a few thousand die-hard spectators roared their appreciation for Alcaraz as the Spaniard collapsed to the Arthur Ashe Stadium court in delight after a famous victory over Sinner, the 21-year-old Italian 11th seed.

“Honestly, I still don’t know I did it,” said Alcaraz after a win which came after he survived a match point in the fourth set.

A shattered Sinner said the defeat was the hardest of his young career.

“I had some tough losses for sure, and this is in the top list,” he said.

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