Kaka was the hero as he opened the scoring with his 100th AC
Milan goal before adding another as the Rossoneri beat Atalanta 3-0.
The Brazilian held a Milan shirt with his name and No 100 printed on the back after squeezing home from a tight angle.
Hot prospect Bryan Cristante grabbed the third, smashing home from distance, in off the base of the left-hand post.
100 not out: Kaka scored his 100th - and 101st - goal for AC Milan as they ran out 3-0 winners
Loving it: Bryan Cristante (left) celebrates after firing home from outside the box
Cristante, 18, signed a contract with Milan last year and played his first game in November.
Monday's match against Atalanta was his second and it was also his first goal for the club.
Before that, good work by Mario Balotelli saw the ball find Kaka in the box and he fired home from close range.
In the end Milan ran out comfortable victors but at times it wasn't easy, with Yohan Benalouane adjudged to have shoved a defender before blasting home so his goal was ruled out.
Doubling up: Kaka's second goal was firing home from close range past Atalanta keeper Andrea Consigli
Ready to rumble: Mario Balotelli came on as a substitute and helped to set up Kaka's second goal
Big hand: AC Milan's new signing Keisuke Honda waves to the crowd before the game
Inter Milan lost ground in their chase for Champions League football
next season with a narrow defeat at Lazio on Monday evening.
Miroslav Klose's late goal handed the Romans a deserved 1-0 victory.
Edy Reja, put in charge at the weekend following the sacking of Vladimir Petkovic, enjoyed a successful start in his second spell at the helm of Lazio.
Inter fell eight points behind Napoli, who are third and hold the last Champions League qualifying spot.
Earlier in the day, Napoli had closed the gap on second-placed Roma to just two points with a 2-0 home triumph over Sampdoria.
Dries Mertens scored twice for Napoli as they claimed their 12th win of the campaign.
Sinisa Mihajlovic tasted his first defeat since taking over Sampdoria in November.
Fifth-place Hellas Verona began 2014 as they ended 2013, with another impressive win.
Sure shot: Lazio's Miroslav Klose scores the winner against Inter Milan
Stunner: Miroslav Klose's shot beats the Inter keeper
Andrea Mandorlini's side beat Lazio 4-1 in their last match before
the winter break and they were 3-1 victors at Udinese on Monday.
Luca Toni put Hellas on their way with two early goals before Roberto Pereyra pegged one back before the break. Juan Iturbe put the result beyond doubt by knocking in Hellas' third 20 minutes from time.
Genoa ended an almost two-month wait for a win in Serie A by beating Sassuolo, 2-0.
Alberto Gilardino scored the opener from the penalty spot before Alberto Bertolacci made it 2-0 before the interval.
Gilardino then saw another penalty saved by Gianluca Pegolo.
Torino's three-match winning streak came to an end in a 3-1 defeat at Parma.
The hosts' Marco Marchionni cancelled out Ciro Immobile's opener in the 34th minute before goals from Alessandro Lucarelli and Amauri wrapped up the victory for the Parma.
Serie A's bottom club Catania stopped the rot with a 2-0 victory over Bologna.
The victory was their first since November 9.
The Brazilian held a Milan shirt with his name and No 100 printed on the back after squeezing home from a tight angle.
Hot prospect Bryan Cristante grabbed the third, smashing home from distance, in off the base of the left-hand post.
100 not out: Kaka scored his 100th - and 101st - goal for AC Milan as they ran out 3-0 winners
Loving it: Bryan Cristante (left) celebrates after firing home from outside the box
Monday's match against Atalanta was his second and it was also his first goal for the club.
Before that, good work by Mario Balotelli saw the ball find Kaka in the box and he fired home from close range.
In the end Milan ran out comfortable victors but at times it wasn't easy, with Yohan Benalouane adjudged to have shoved a defender before blasting home so his goal was ruled out.
Doubling up: Kaka's second goal was firing home from close range past Atalanta keeper Andrea Consigli
Ready to rumble: Mario Balotelli came on as a substitute and helped to set up Kaka's second goal
Big hand: AC Milan's new signing Keisuke Honda waves to the crowd before the game
Miroslav Klose's late goal handed the Romans a deserved 1-0 victory.
Edy Reja, put in charge at the weekend following the sacking of Vladimir Petkovic, enjoyed a successful start in his second spell at the helm of Lazio.
Inter fell eight points behind Napoli, who are third and hold the last Champions League qualifying spot.
Earlier in the day, Napoli had closed the gap on second-placed Roma to just two points with a 2-0 home triumph over Sampdoria.
Dries Mertens scored twice for Napoli as they claimed their 12th win of the campaign.
Sinisa Mihajlovic tasted his first defeat since taking over Sampdoria in November.
Fifth-place Hellas Verona began 2014 as they ended 2013, with another impressive win.
Sure shot: Lazio's Miroslav Klose scores the winner against Inter Milan
Stunner: Miroslav Klose's shot beats the Inter keeper
Luca Toni put Hellas on their way with two early goals before Roberto Pereyra pegged one back before the break. Juan Iturbe put the result beyond doubt by knocking in Hellas' third 20 minutes from time.
Genoa ended an almost two-month wait for a win in Serie A by beating Sassuolo, 2-0.
Alberto Gilardino scored the opener from the penalty spot before Alberto Bertolacci made it 2-0 before the interval.
Gilardino then saw another penalty saved by Gianluca Pegolo.
Torino's three-match winning streak came to an end in a 3-1 defeat at Parma.
The hosts' Marco Marchionni cancelled out Ciro Immobile's opener in the 34th minute before goals from Alessandro Lucarelli and Amauri wrapped up the victory for the Parma.
Serie A's bottom club Catania stopped the rot with a 2-0 victory over Bologna.
The victory was their first since November 9.
