Striker Bayo will have a scan on a knock and is a major doubt for Celtic's Ladbrokes Premiership clash with St Mirren at Parkhead on Wednesday.
Ryan Christie returns from a two-match domestic ban but Tom Rogic has inflammation around the knee and will be monitored. Christopher Jullien has trained after illness while Olivier Ntcham (ankle) is also back in training.
St Mirren expect to have Gary McKenzie back after the defender missed the defeat by Kilmarnock.
Loan player Calum Waters also returns after being forced to sit out the game against his parent club.
Celtic provisional squad: Forster, Frimpong, Bauer, Elhamed, Ajer, Bolingoli, Jullien, Taylor, Rogic, Bitton, Brown, McGregor, Ntcham, Forrest, Edouard, Christie, Hayes, Morgan, Bayo, Elyounoussi, Gordon.
St Mirren provisional squad: Hladky, P McGinn, Waters, Broadfoot, MacKenzie, McLoughlin, Magennis, Erhahon, S McGinn, Flynn, Foley, Andreu, Djorkaeff, MacPherson, Durmus, Mullen, Morias, Obika, McAllister, Cooke, Lyness.