The England Under-21 international had to come off during Saturday’s 1-1 draw at Leeds due to a calf problem and is set to miss out.
Tomkins, usually a centre-half, has been playing in midfield as Papa Bouba Diop remains sidelined with a hamstring injury.
Winger Ricardo Vaz Te will be out for at least another week with his hamstring problem while Winston Reid (head), Julien Faubert (groin) and Guy Demel (thigh) are still carrying knocks.
Ravel Morrison, who made his first Hammers appearance as a late substitute at Elland Road, could therefore be in line for a full debut while Gary O’Neil is also on standby.
Stoke could face a battle to keep Xherdan Shaqiri as reports have claimed Mark Hughes wants him at Southampton next season.
Bayern Munich have entered the race to Emre Can, who continues to talk up a move away from Liverpool this summer.