Inter's Champions League hopes received a huge boost with a late comeback and a 3-1 win against Lazio in Serie A.
Felipe Anderson had given the visitors a first-half lead at San Siro, robbing Francesco Acerbi of possession and dispatching past Andre Onana.
Numerous chances for an equaliser went begging for the hosts in the second half, which looked set to result in yet another home loss for the Nerazzurri.
However, Martinez smashed home an equaliser after 77 minutes, with Robin Gosens putting his side ahead befre Martinez added further gloss to the scoreline in a rallying finish from Simone Inzaghi's men.
The hosts were the stronger of the two sides early on, Henrikh Mkhitaryan proving to be an effective attacking outlet by former Provedel into a save before tucking home after Joaquin Correa's cutback, though his celebrations were cut short by an offside flag.
Lazio swiftly responded, taking the lead on the half hour mark through Anderson who won possession from Acerbi and exchanged a neat one-two with Luis Alberto before slotting beneath Onana.
The Cameroonian needed to be alert to prevent Lazio from extending their lead before the break, parrying Ciro Immobile's low drive away from the far corner, then collecting Alessio Romagnoli's header from point-blank range from the following corner.
Inter pushed for an equaliser immediately after the restart, Nicolo Barella volleying a fierce strike agonisingly wide of the post, though Lazio remained a threat and Onana had to keep Alberto's fine effort at bay.
A late comeback soon turned the match on it's head, Martinez latching onto Lukaku's inviting pass and smashing past Provedel, before Lukaku was again the provider by floating a cross to the far post that Gosens volleyed home.
There was still time for further celebration, Martinez pouncing on Matias Vecino's loose back pass and bearing down on goal, securing his brace at the second attempt after Provedel saved his initial effort.
What does it mean? Inter receive huge boost
Entering the game with three consecutive home defeats in Serie A, failing to score in all, Inter's top-four ambitions were significantly under threat.
It appeared that poor run would continue against Lazio but a late comeback, with all three goals occurring after the 77th minute, provided a timely boost.
Inter leapt to fourth in the standings with the win, with 57 points putting them level with Milan and Roma.
Lukaku leading by example
Though not on the scoresheet, Lukaku made the difference for Inter in their fightback by providing the assists for both Martinez and Gosens.
The Belgian created five chances for his teammates, more than anyone else on the field.
Masterful Martinez
Coming off the bench, Martinez's introduction changed the flow of the game and he finished with six attempts on goal, more than anyone else.
As a result, Martinez took his Serie A total this season to 17 – becoming the third Inter player to score more than 15 goals for three campaigns in a row in the last 55 years, joining Christian Vieiri and Mauro Icardi with that honour.
What's next?
Inter travel to face Verona on Wednesday, while Lazio will look to bounce back at home to Sassuolo on the same day.
