Nishikori beats Raonic in US Open tennis

It was the late, late show for Kei Nishikori and Milos Raonic who played until 2:26am local time in New York before the Japanese prevailed in five sets.

Japan's Kei Nishikori (pic) has beaten Canada's Milos Raonic to reach the US Open quarter-finals. (AAP)

Japan's Kei Nishikori booked a US Open quarter-final berth on Tuesday morning with a five-set victory over Milos Raonic that equalled the latest-finishing contests in tournament history.

Nishikori, the 10th seed, defeated the fifth-seeded Canadian 4-6 7-6 (7/4) 6-7 (6-8) 7-5 6-4 and will face Australian Open champion Stan Wawrinka for a place in the semi-finals.

The 2:26am finish local time equalled the record for the latest at the US Open shared by two prior contests: Philipp Kohlschreiber's 6-4 3-6 4-6 6-3 6-4 third-round win over John Isner on September 3, 2012 and Mats Wilander's 7-6 (7-3) 3-6 1-6 7-6 (8-6) 6-4 win over Swedish compatriot Mikael Pernfors in a second round match in 1993.