Sebastiano Esposito made history while Romelu Lukaku got two goals and an assist as a depleted Inter thumped Genoa 4-0 at home to ensure it will end 2019 top of Serie A.
Inter scored twice in 99 seconds just after the half-hour mark to set up the emphatic win at San Siro on Saturday, Lukaku netting a header that was followed up by a Roberto Gagliardini strike as Antonio Conte's men moved above Juventus on goal difference.
At 17, Esposito became Inter's youngest player to start a Serie A match in the 21st century as Conte shuffled his pack due to a host of absentees and the teenager made sure of victory with a second-half penalty, before Lukaku – who had allowed him to take the spot-kick – struck once more.
Former Inter midfielder Thiago Motta is likely to lose his job as Genoa boss after his uninspired side was left with only two wins from 17 league games heading into the festive break.
Esposito had the first chance as he forced a low save from Ionut Radu, who then had to produce an even better stop from a looping Gagliardini header.
There was little Radu – who is on loan at Genoa from Inter - could do to prevent the opener, though, Lukaku stooping to power in Antonio Candreva's right-wing cross from eight yards.
The goalkeeper got a hand on Gagliardini's 12-yard strike but could not prevent it from crossing the line after a deflection off Cristian Romero, Lukaku having shown good strength to set up his team-mate.
Samir Handanovic made his first save from Antonio Sanabria but Inter got a 64th-minute penalty when Kevin Agudelo tripped Gagliardini and Esposito did the rest, powering a low strike beyond Radu to become the club's second youngest league scorer.
Lukaku's second was the pick of the goals, the striker collecting a pass from Candreva, cutting inside from the right and arrowing an unstoppable effort into the top corner.
What does it mean? Inter back on track despite absences
Inter had Lautaro Martinez and Marcelo Brozovic suspended, while Alexis Sanchez, Nicolo Barella and Kwadwo Asamoah were all injured, with Stefano Sensi just fit for bench.
Considering it came into the game winless in three across all competitions and having crashed out of the Champions League, it will be thrilled with a comprehensive victory. On the three previous occasions the Nerazzurri have had 42 points after 17 matches, they have won the league.
Lukaku steps up for Inter
With Martinez out, Lukaku produced a fine display in attack and could have easily ended with a hat-trick had he opted to take the penalty or converted a great chance just after the break. Gagliardini also enjoyed an impressive outing.
Romero struggles in defence
Romero struggled along with most of his Genoa team-mates as he was outmuscled by Lukaku ahead of the second goal and then deflected Gagliardini's effort in as he tried to make up for it.
Just after the interval, Radu somehow saved Lukaku's effort, which had only come about after Romero cleared the ball straight into his path.
After the break, leader Inter will return to action with a testing match away to Napoli on January 6, a day after Genoa hosts Sassuolo.