Milan were comfortable 3-1 winners.
Allegri explained: "With Kevin-Prince Boateng leaving I lacked a wide attacker, plus my idea was to go back to two strikers because Mario Balotelli needs a partner who runs into space. Riccardo Montolivo did very well as a trequartista.
"We didn't have much time to test out this new system and I think El Shaarawy can learn to be a support striker, but of course it'll take some more practice. There is absolutely no El Shaarawy problem."
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