Gian Piero Gasperini admitted Atalanta “belong up there” in the race for the top four and victory away to Cagliari was “a show of maturity”.
Hans Hateboer got the decisive header in Sardinia, meeting a cross from Timothy Castagne.
The win put them in joint fifth place with Lazio and Roma, just one point behind Milan, and arrived days after beating Juventus 3-0 in the Coppa Italia.
“This is a great victory, clearly different to the others and played less well, but it was against a more defensive and physical side who made it very difficult for us to play. There are many teams crammed together up there, all the way from Torino or even Parma. That’s why a success like this gives us extra belief”, told coach.