Zlatan ramped up his return from injury with five minutes of the bench, his first appearance since scoring twice against Napoli in late November.
His return is about the only piece of good news for Pioli ahead of the encounter, who continues to have his squad trimmed thin with injuries and COVID-19 cases.
Ante Rebic and Rade Krunic are both definitely out after testing positive for the virus, while injury clouds hover over Matteo Gabbia as well as key midfielders Ismael Bennacer and Alexis Saelemaekers.
That means the lineup will likely look very similar to the one from the weekend, though Diogo Dalot could come in at right-back to replace Davide Calabria.
In midfield Sandro Tonali should remain having seen an increase to his involvement in recent months, alongside Franck Kessie whose penalty confirmed victory on Saturday.
There could be a rare start in midfield for Daniel Maldini, and he could be joined by Hakan Calhanoglu after the Turk played just the last half hour in the league.
Lack of other options will force Samu Castillejo to have to go again on the right-hand side, with the position up front up for debate.
Ibra would be a more than welcome addition into the side, but whether or not he is fully fit is an entirely different question.
Rafa Leao has been involved in goals in four of his last five games and with Ibra still likely to be short of complete fitness, the Portuguese will likely need to start again.
Zlatan should be able to play more of a part in this tie, though, and will relieve some pressure on a tiring Milan outfit.