Atalanta v AC Milan - Serie A
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Christian Pulisic exited AC Milan's 2-1 defeat to Atalanta in the 38th minute due to injury on Friday, causing some concern for the club at a busy period of the season. The American, who is in the midst of arguably the best club season of his career, was clipped on his left leg by Atalanta midfielder Mario Pasalic while battling for the ball, which caused him to slip and lose balance on planting that left foot on the ground. Currently listed as a calf injury, Pulisic will undergo an MRI on Monday, according to Sky Italia.

Concern could be seen on manager Paulo Fonseca's face when Pulisic left the pitch for Ruben Loftus-Cheek -- and it makes sense given his importance to Milan this season. He's been the most in-form player to put on a rossoneri shirt this season, registering eight goals and six assists in all competitions. Pulisic entered Friday with goal contributions in back-to-back starts after scoring against Slovan Bratislava in the Champions League and registering an assist against Empoli in Serie A play -- all while Milan's form improved following a poor start to the season.

Milan saw a November streak of seven matches without a defeat snapped on Friday. Pulisic's form alongside a resurgent Rafael Leao was critical to that run. If the injury causes Pulisic to miss significant time, Samuel Chukwueze will be someone expected to contribute more for the club.

Leaving the pitch, Pulisic could walk off under his own power with assistance leaning on a staff member, but entering the festive fixtures period, matches will come thick and fast for Milan. With a Champions League fixture against Red Star Belgrade on the horizon, they'll play three matches in nine days. Here's a look at their next five matches:

The hope is that the withdrawal is just precautionary and that Pulisic will be back in action on Wednesday for Milan, but this will be something to watch over the next few days.