London - Kei Nishikori overcame an arm injury to reach his first Wimbledon quarter-final on Monday with a gritty 4-6, 7-6 (7/5), 7-6 (12/10), 6-1 win over Latvian qualifier Ernests Gulbis.
The 28-year-old Nishikori is the first Japanese man to reach the quarter-finals at Wimbledon since Shuzo Matsuoka in 1995.
His reward is a last-eight match-up against either three-time champion Novak Djokovic or unseeded Karen Khachanov of Russia.
Nishikori needed lengthy treatment and a medical timeout on a right arm injury in the first set and had to save set points in the third.
Gulbis, ranked 130 and who came through qualifying, had shocked fourth seeded German Alexander Zverev in the third round.
But having played three successive five-set matches in the main draw to get this far, he ran out of steam.
A nasty fall, which required a medical time out on his left knee, doomed Gulbis's bid to become just the sixth qualifier to reach the last-eight at Wimbledon.
Wimbledon results on Monday, the seventh day of the 2018 championships (x denotes seeded player):
Roger Federer (SUI x1) bt Adrian Mannarino (FRA x22) 6-0, 7-5, 6-4
Kevin Anderson (RSA x8) bt Gael Monfils (FRA) 7-6 (7/4), 7-6 (7/2), 5-7, 7-6 (7/4)
Milos Raonic (CAN x13) bt Mackenzie McDonald (USA) 6-3, 6-4, 6-7 (5/7), 6-2
John Isner (USA x9) bt Stefanos Tsitsipas (GRE x31) 6-4, 7-6 (10/8), 7-6 (7/4)
Novak Djokovic (SRB x12) bt Karen Khachanov (RUS) 6-4, 6-2, 6-2
Kei Nishikori (JPN x24) bt Ernests Gulbis (LAT) 4-6, 7-6 (7/5), 7-6 (12/10), 6-1
Rafael Nadal (ESP x2) bt Jiri Vesely (CZE) 6-3, 6-3, 6-4
Suspended due to darkness:
Juan Martin del Potro (ARG x5) leads Gilles Simon (FRA) 7-6 (7/1), 7-6 (7.5), 5-7
Dominika Cibulkova (SVK) bt Hsieh Su-Wei (TPE) 6-4, 6-1
Jelena Ostapenko (LAT x12) bt Aliaksandra Sasnovich (BLR) 7-6 (7/4), 6-0
Daria Kasatkina (RUS x14) bt Alison Van Uytvanck (BEL) 6-7 (6/8), 6-3, 6-2
Angelique Kerber (GER x11) bt Belinda Bencic (SUI) 6-3, 7-6 (7/5)
Kiki Bertens (NED x20) bt Karolina Pliskova (CZE x7) 6-3, 7-6 (7/1)
Julia Goerges (GER x13) bt Donna Vekic (CRO) 6-3, 6-2
Serena Williams (USA x25) bt Evgeniya Rodina (RUS) 6-2, 6-2
Camila Giorgi (ITA) bt Ekaterina Makarova (RUS) 6-3, 6-4