Henrikh Mkhitaryan's superb second-half volley helped Inter overcome a stubborn Udinese in Serie A on Saturday, claiming a 3-1 win at San Siro.
Romelu Lukaku's 20th-minute penalty after Denzel Dumfries was brought down saw the hosts initially lead, only for Sandi Lovric's breakaway finish to reel them in before the break.
But just as it looked like the Nerazzurri would be forced to settle for a point, the Armenia international rode to their rescue with an excellent 73rd-minute strike.
Martinez made sure of the points in the 89th minute as Simone Inzaghi's side stretched their lead over third-place Milan to three points, ahead of the congested European race beneath them.
Inter entered the match with a verve and energy their visitors struggled to handle early on, and won a penalty after Walace was deemed to have fouled Dumfries by the VAR.
Lukaku initially saw his first effort saved by Marco Silvestri, but the goalkeeper was adjudged to be off his line and the Belgian made no mistake with his second attempt.
Yet the hosts failed to capitalise on their advantage, and Udinese deservedly drew level two minutes from the interval when Lovric finished off a shrewd counter-attack.
Dumfries fluffed his lines when presented with a chance to restore Inter's lead with a cross from Mkhitaryan, who achieved that feat with 17 minutes of normal time remaining when he lifted Federico Dimarco's square delivery beyond Silvestri.
Martinez added a late touch of gloss by powering a strike home in the closing stages to ensure there would be no late capitulation from Inter.
What does it mean? Inter move clear behind Napoli
With the Serie A title race looking more and more like a done deal by the day, the battle to see who can be the rest of the best is hotting up.
After dropping points last time out, it is advantage second-placed Inter once again, with their win here ensuring they have some daylight between them and the rest of the pack.
Lukaku ends long wait for top-flight strike
Lukaku's goal ended a 189-day drought in Serie A for the Belgium international, his previous goal coming way back in August against Lecce.
His penalty also marked his first home goal in the competition since May 2021, coincidentally also against Udinese.
Lovric carries weight for visitors
Seizing a great chance to level matters heading towards half-time wasn't the only thing the Slovenia international did for his side today.
Only Issac Success had more shots for Udinese than his two, while he also won back possession more times (seven) than any of his team-mates bar Kingsley Ehizibue (eight).
What's next?
Inter return to Champions League action with a last-16 first leg tie against Porto on Wednesday before facing Bologna the following Sunday, when Udinese will host Spezia.
