Mateo Retegui has scored four goals to lead Atalanta's 5-0 demolition of Hellas Verona, while Santiago Giménez scored in his Serie A debut for AC Milan.

Italy striker Retegui took his league-leading tally to 20 goals for the season after scoring a first-half hat-trick before adding his fourth after the break. The second-leading scorer is Fiorentina's Moise Kean with 15 goals.

Retegui found the net in the 21st, 25th, 44th and 56th minutes. Ederson made it 3-0 in the 37th.

The lopsided win lifted Atalanta to within one point of Inter Milan in second. Leader Napoli are four points ahead of third-placed Atalanta.

Gimenez started making good on the 30 million euros ($A49.5m) plus bonuses Milan reportedly paid Feyenoord for the Mexico striker.

Giménez took a pass from Christian Pulisic, put the ball on his left foot and drilled in his team's second goal in a 2-0 win over Empoli. Rafael Leão opened the scoring with a header.

Both sides finished with 10 men. Milan defender Fikayo Tomori saw a second yellow in the 55th, but Empoli's advantage only lasted 10 minutes before Luca Marianucci got a direct red.

Giménez made his club debut earlier in the week when he had an assist in a 3-1 win over Roma in the Italian Cup.

Torino and Genoa drew 1-1.