Felipe Caicedo tapped in after a dogged run and drive from Immobile, who then converted a penalty awarded for handball and in the 20th minute finished off another break in the box.

Defender Bastos came on after the break on Saturday to make it 4-0 before Immobile fired in a second penalty awarded after video review to complete his hat-trick for a season tally of 23 goals.

Karol Linetty netted Samp's consolation goal before teammate Julian Chabot was dismissed with a direct red card.

"We wanted to start well into the second half of the season and not undervalue this game," Immobile said.

"My teammates always help me do well, so part of the merit is theirs.

"We must keep our feet on the ground, which is what we always tell each other when we train. For the time being, our goal is a Champions League place."

The Rome side fill the third of four places for the elite event. They sit third on 45 points with a game in hand, one behind Inter Milan, who visit Lecce on Sunday when leaders Juventus (48) are also at home to Parma.

Samp (19) have a five-point buffer to the drop zone and saw Sassuolo move on to 22 after a 2-1 home rally against Torino.

Il Toro went ahead from a deflected Tomas Rincon drive but the hosts bounced back after the break as Jeremy Boga drilled home and set up Domenico Berardi's winner on 73. Torino are eighth on 27 points.

Fiorentina took home a 2-0 win at Napoli and drew level on 24 points with their Neapolitan hosts and Udinese.

Federico Chiesa struck off Marco Benassi for the Florentines' first-half opener and Dusan Vlahovic stunned David Ospina for the second on 74 minutes.

Matchday 20 ends on Monday when fourth-placed Atalanta (35) host backmarkers SPAL.

Australian Associated Press