Inter Milan made sure the gap separating them from runaway Serie A leaders Napoli stayed at 15 points with a 3-1 success over Udinese on Saturday.

Romelu Lukaku, Henrikh Mkhitaryan and Lautaro Martinez all scored in a hard-fought win against ninth-placed Udinese, who have won only once in their last 15 league matches.

Simone Inzaghi's side stay second and are three points ahead of local rivals AC Milan, who beat Monza 1-0 earlier on Saturday, but are a long way behind rampant Napoli after their 2-0 win at Sassuolo on Friday.

"Udinese are a very physical side with good technique who cause you a lot of problems, as we already saw in the reverse fixture (lost 3-1)," said Inzaghi to Sky.

"It's a good victory that allows us to keep going."

Lukaku gave Inter the lead from the penalty spot at the second attempt in the 20th minute, his first league goal since their opening match of the season at Lecce.

But Sando Lovric gave the away side a deserved equaliser with a powerful strike two minutes before half-time.

From there Inter struggled to break down spirited Udinese, Edin Dzeko missing a great chance a minute before a piece of magic from Mkhitaryan which swung the match in the hosts' favour.

Former Armenia captain Mkhitaryan swept home a beautiful first-time finish from Federico Dimarco's layoff in the 73rd minute to send a wave of relief around the San Siro.

In the final minute substitute Martinez lashed in his eighth goal in all competitions since the World Cup after collecting Danilo D'Ambrosio's long pass, giving Inter a big win ahead of the Champions League visit of Porto on Wednesday.

"Obviously it's really important to win the home leg," said Mkhitaryan to Sky.

"We know Porto's strengths, I played against them last season in a friendly with Roma. We need to be ready for them."

Milan revival continues

Milan's season is creaking back into gear and Junior Messias lashed in a powerful strike from the edge of the area in the 31st minute to earn a third league win since the new year.

"We had chances to add more... but given the situation we find ourselves in we need to keeping building our belief getting results," coach Stefano Pioli told DAZN.

"We're in a battle for the Champions League, but if we keep clean sheets we have the quality to win games."

Saturday's win against their Lombardy rivals was Milan's third single-goal victory in a row in all competitions and came after Tuesday's 1-0 Champions League win over Tottenham Hotspur.

Monza, whose unbeaten record ends at eight matches, dropped down a place to 11th thanks also to Bologna's late 2-1 win at struggling Sampdoria.

Milan were still not back to their very best but could have easily won by more, Michele Di Gregorio having to make a series of saves before Messias crashed home his third league goal of the season.

Rafael Leao clipped a speculative effort off the post in the 19th minute and six minutes later his weak finish at the end of a counter-attack was pushed out by Di Gregorio, who then had to pounce to stop Brahim Diaz from scoring.

Fikayo Tomori forced another good save from Di Gregorio with a snap shot just before the half-hour mark, but the best chance of the lot was wasted by Theo Hernandez in the 56th minute.

The France left-back was sent charging through by Leao but misdirected his chipped finish into the side netting.

Milan then had to weather a late Monza storm as Patrick Ciurria struck a low shot off the post before Di Gregorio kept out Sandro Tonali and Matteo Pessina denied struggling summer signing Charles De Ketelaere.