Injured Richard Gasquet joins Kei Nishikori in being forced to withdraw from Wimbledon

Gasquet - who reached the semi-finals at last year's tournament - was forced to retire with a back injury with his fellow Frenchman Jo-Wilfried Tsonga leading 4-2 in the first set on Court One.

Tsonga - who won an epic five-set match against John Isner in the third round on Sunday after recovering from losing the first two sets to win the fifth set 19-17 - is likely to face tournament favourite Andy Murray in the quarter-finals providing the Scotsman overcomes Nick Kyrgios in the last 16.

Nishikori was forced to retire midway through his fourth round encounter with Marin Cilic at Wimbledon after aggravating an injury.

The Japanese fifth seed failed to top 100mph with his serve in a 16-minute first set as he eventually withdrew trailing 6-1 5-1 on Court Two.

Nishikori, who swallowed a pill given by the trainer at the previous change of ends, shook his head at the umpire to indicate he could not longer continue before going up to Cilic to shake hands.

"It was too much pain I could not really compete today. Every point I played it got worse. I did not want to but I had to retire," Nishikori told a news conference.

2-Andy Murray (GB) beat 15-Nick Kyrgios (Australia) 7-5 6-1 6-4

28-Sam Querrey (U.S.) beat Nicolas Mahut (France) 6-4 7-6(5) 6-4

3-Roger Federer (Switzerland) beat Steve Johnson (U.S.) 6-2 6-3 7-5

9-Marin Cilic (Croatia) beat 5-Kei Nishikori (Japan) 6-1 5-1 (Nishikori retired)

32-Lucas Pouille (France) beat 19-Bernard Tomic (Australia) 6-4 4-6 3-6 6-4 10-8

12-Jo-Wilfried Tsonga (France) beat 7-Richard Gasquet (France) 4-2 (Gasquet retired)

6-Milos Raonic (Canada) beat 11-David Goffin (Belgium) 4-6 3-6 6-4 6-4 6-4

10-Tomas Berdych (Cze) v Jiri Vesely (Cze) 4-6 6-3, 7-6 (8) 6-7 (9) (Play suspended for bad light)