Milan are travelling for the first of two decisive games against FC Porto, with Davide Calabria possibly at left-back and Rade Krunic seems set to start in the attacking trident behind Olivier Giroud.
The match at the Estadio do Dragao kicks off at 20.00 UK time.
Ciprian Tatarusanu is set to make his debut in the Champions League when Milan visit Porto, while Davide Calabria could start at left-back in the absence of Theo Hernandez.
Mike Maignan injured his wrist during the international break with France, while Theo Hernandez returned with coronavirus.
Brahim Diaz has since tested positive too and Pioli seems set to start returning Krunic in his place. Alexis Saelemaekers and Rafael Leao is set to complete the trident.
Franck Kessie is suspended after the red card against Atletico Madrid, meaning Ismael Bennacer and Sandro Tonali will take place in the middle of the park.
Milan are in desperate need of points, as Sergio Conceicao has an almost full squad to pick from in Porto.
Mbemba is the only player absent, while Pepe should be in the heart of the defence alongside another veteran, Ivan Marcano.
Probable line-ups: Porto vs. Milan
Porto (4-4-2): Diogo Costa; Joao Mario, Pepe, Marcano, Wendell; Uribe, Sergio Oliveira, Otavio, Corona; Diaz, Taremi
Milan (4-2-3-1): Tatarusanu; Kalulu, Tomori, Kjaer, Calabria; Bennacer, Tonali; Saelemaekers, Krunic, Leao; Giroud