The Hammers suffered a humiliating 4-1 loss to Swansea City on Saturday.
Former West Ham United captain Nigel Reo-Coker has told BBC Radio 5 Live's MOTD 2 Extra that Hammers duo Mark Noble and James Collins must improve the character of their foreign teammates.
David Moyes' side suffered a dismal 4-1 loss to Swansea City on Saturday afternoon at the Liberty Stadium, as Ki Sung-Yueng, Mike van der Hoorn, Andy King and Jordan Ayew scored for Carlos Carvalhal's side.
Michail Antonio scored a late consolation goal in the 79th minute, but the Hammers have now slipped into 14th place and are only three points above the Premier League relegation zone.
Reo-Coker, who turned out for the Hammers during a three-year period between 2004 and 2007, urged Noble and Collins to help the Hammers' foreign players learn what it means to play for West Ham.
"They’ve got Mark Noble, they’ve got James Collins and they have both been at the club for a long period of time. They’ve got character there," Reo-Coker said.
"They need to get everyone to buy into the club in what it means to play for West Ham. That’s a difficult thing. Sometimes you need a good foundation of solid British players.
"It is about them stepping up to the plate to get the foreign players to buy into it."
The Hammers now have two crucial matches against Burnley at the London Stadium on Saturday before travelling to the south coast to face 19th-placed Southampton after the international break, before a difficult run of games.
They then face Chelsea, Stoke City, Manchester City and Arsenal following their clash against Southampton, with injury problems beginning to pile up.
Angelo Ogbonna and Collins were ruled out of Saturday's loss, while WInston Reid was forced off in the first half just days after the Hammers confirmed they had sold Jose Fonte to Chinese Super League side Dalian Yifang.