Inter came from behind to beat Bologna 3-1 at the Stadio Renato Dall'Ara on Saturday.
Tommaso Pobega put Bologna ahead after just 10 minutes with a low left-foot shot.
Pobega fired one shot just wide, then hit the crossbar with another effort.
Marcus Thuram headed home from Nicolo Barella's cross in the 44th minute.
Thuram's goal was his fourth in five Serie A games this season.
Coach Cristian Chivu sent on Andy Diouf and Carlos Augusto with 20 minutes left.
Within a minute, Diouf found Zielinski, whose low cross set up Augusto to tap home.
Ange-Yoan Bonny finished from Augusto's pass in the 83rd minute to make it 3-1.
The win put Inter three points clear at the top of Serie A.
Bologna stay just one point above the drop zone after the defeat.
Bologna still wait for a home win, with the last one coming on April 12.
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