La Dea badly needed this boost, as they had scraped just one point from the last four Serie A games and saw their lead twice clawed back in Bergamo this evening by Olivier Giroud and Luka Jovic.
However, after Davide Calabria saw red for a second bookable offence, Aleksei Miranchuk set up fellow substitute Luis Muriel for a divine back-heel flick from six yards to seal the 3-2 victory.
“I never had doubts on the character of this squad over the years,” Gasperini told DAZN.
“There are some games where you struggle, we are also playing in the Europa League and were not always as determined or fuelled by the same adrenaline as usual. There are a lot of fixtures, Europe gives us a lot, but takes away too in terms of energy, injuries and focus.
“When we are able to prepare and are faced with a team like Milan, we bring out this extraordinary performance.”
Lookman said last week that he had never worked so hard in training as he did with Gasperini, which seemed to surprise the coach.
“He never did anything, then! Lookman cannot play every game like tonight, or he’d be amazing, but he is doing very well this season. He has some dips and troughs, but that is normal. What he must learn from this group is to share the same spirit, determination and realise when it’s not your day, then you have to work for the team.”
Gasperini also surprised a few in the crowd when he substituted Lookman and De Ketelaere for Miranchuk and Muriel, who went on to combine for the winning goal.
“More than surprised, they were jeering!” said the coach. “I hope they remember next time to wait before jeering a substitution. Muriel scored an extraordinary goal, but I see him do this a lot in training, so they do not come out of nowhere. I tell him he ought to do them in the match situation and tonight he did.”
There seemed to be a tactical shift in the second half when Charles De Ketelaere moved further wide left and Lookman was more central.
“Milan are a very versatile team, they can change face and we can do it too. They played with four at the back, but really it was three with Alessandro Florenzi moving into midfield. So we took a while to adjust and get the right movements.
“We stopped De Ketelaere chasing down Theo Hernandez too much and he did better there. When you face a team like Milan that changes constantly, you have to be well-prepared.
“There were a few similar performances this season where we did not get the result we deserved.”
De Ketelaere at first seemed a little over-awed by facing his parent club and missed a pair of real sitters.
“There were a couple of big chances, really! I have said for a while that he is growing, improving and it’s a pleasure to work with him.”