Stefano Pioli "will work something out" after the "decisive figure" of Rafael Leao was ruled out of next weekend's clash with Napoli following a red card in the 2-1 win over Sampdoria.
Leao had been sensational in the first half at Stadio Luigi Ferraris, setting up Junior Messias' sixth-minute opener with one of three key passes – a total not bettered by anyone on the pitch.
However, his match ended just two minutes into the second half when he received a second booking after he struck Alex Ferrari in the face when attempting an overhead kick.
Samp pulled level through Filip Djuricic, but Milan sealed a fourth win in six Serie A games this season when Olivier Giroud powered home from the penalty spot after Gonzalo Villar had handled in the area.
The champions have now won three successive Serie A games against Sampdoria for the first time since September 2016.
Second-placed Milan are level on points with leaders Napoli, who visit San Siro on Sunday, and Pioli accepted he might have to play a different way in the absence of Leao.
"Both teams are missing a lot, but we're missing Leao and Ante Rebic; both players who cover that role," he told Sky Sport Italia.
"We had to play 50 minutes with 10 men. We know there's a big Champions League game coming up [at home to Dinamo Zagreb on Wednesday], so we'll focus on that first and then see what to do against Napoli.
"Rafa is becoming a decisive figure in our attack, but we have other alternatives and will work something out with different characteristics.
"I saw Leao joking around a lot in the warm-up, but I told him he tends to play well when he's that relaxed and he said 'don't worry, boss'. In hindsight, I should've worried.
"It's disappointing. I had told him to be careful on the yellow, but he wanted to attempt this move. Never mind, someone else will play."
Samp went agonisingly close to rescuing a point in a late scramble as Mike Maignan twice denied Manolo Gabbiadini either side of a Fabio Quagliarella effort that struck the post.
Pioli was thrilled with his side's ability to grind out the result and believes it is evidence they are moving in the right direction.
"We played a good first half and could've scored more goals, but this was a hard-fought victory," he added.
"We had to grit our teeth when we went down to 10 men and the lads worked hard on every ball. Sampdoria had already drawn with Juventus and Lazio here, so it was by no means easy.
"We had told ourselves we wanted to make fewer technical errors and I think we did that today, so we're on the right track."