The former Real Madrid star, and Juventus Forward nets a hat-trick against Cagliari in the second half of the game.
The second-half was all one-way traffic with 34-year-old Ronaldo breaking the deadlock just after the interval.
He added a second from the penalty spot on 67 minutes with Argentina’s Gonzalo Higuain coming off the bench to strike a third on 81 minutes, before Ronaldo completed his hat-trick a minute later.
Juve are three points ahead of Inter in the table with Antonio Conte’s side travelling to Napoli later on Monday, looking to keep pace with the eight-time reigning champions.
Atalanta closed to within a point of fourth-placed Roma, who lost 2-0 to Torino on Sunday, with a 5-0 rout of Parma, having also beaten AC Milan by the same scoreline before the winter break.The side from Bergamo were already three goals up before the break thanks to Alejandro Gomez, Remo Freuler and Robin Gosens, with Josip Ilicic adding a double in a nine minute second-half spell