The duo missed Thursday's defeat to Leicester City, and although Allardyce affirmed that their problems were minor, they are expected to keep Branislav Ivanovic company in the Baggies' treatment room.
Conor Gallagher could therefore earn a recall to the team over Callum Robinson, who only lasted 45 minutes at the King Power, but Conor Townsend will hope to keep his place at left-back over Gibbs even if the ex-Arsenal man is passed fit.
Semi Ajayi is pushing for a recall to the defence and could be granted it over Dara O'Shea here, and while Allardyce has options for change in midfield, Okay Yokuslu and Ainsley Maitland-Niles should continue there for now.
West Brom possible starting lineup:
Johnstone; Furlong, Ajayi, Bartley, Townsend; Pereira, Yokuslu, Gallagher, Maitland-Niles, Phillips; Diagne
Watch the Sports Mole Football Shorts prediction for this game below: