They move to 31 points from 16 games, with a better goal difference than Lazio, who won 2-1 at Sampdoria Saturday. Sampdoria are ninth on
22 points, while Cagliari are 12th on 20.

Mertens controlled the ball inside the box to find the far corner in the 34th minute and sewed up victory in the 69th and 72nd.

Marek Hamsik tapped in just before half-time after Lorenzo Insigne hit the bar, and Piotr Zielinski drilled home a fast drive in the 51st.
Later in Turin, a city derby between leaders Juventus (36) and Torino highlights the Sunday programme.