Liverpool goalkeeper Simon Mignolet was dropped for his side's Premier League clash with title rivals Arsenal at Anfield on Sunday.
German Loris Karius came in between the posts and Mignolet was not even named on the bench by manager Jurgen Klopp.
The 29-year-old Belgium international had started Liverpool's four previous games, conceding six goals.
British press reports said Mignolet was not believed to be ill or injured.
Karius, 24, took over from Mignolet at the start of last season after arriving from Mainz, but lost his place to the former Sunderland goalkeeper in December after some shaky performances.
Arsenal manager Arsene Wenger, meanwhile, named Alexis Sanchez in his starting XI for the first time this season after the Chilean forward overcame an abdominal strain.
Star signing Alexandre Lacazette dropped to the bench, with Danny Welbeck starting up front.
