Martinez scored in each half which took his tally for the season to 23, while there were also goals from Marcus Thuram, Hakan Calhanoglu and Nicolo Barella after Gianluca Mancini had levelled for the visitors, for whom Lorenzo Pellegrini struck late on at San Siro.
AC Milan will kick off at Napoli on Monday evening knowing anything less than a win will all but hand the title to their derby rivals.
Bologna began their preparations for next week's Europa League quarter-final clash with Aston Villa with a 2-1 victory over Cremonese.
Joao Mario and Jonathan Rowe gave Bologna an early lead before Federico Bonazzoli replied late for the hosts and both teams finished the game with 10 men after Youssef Maleh and Lewis Ferguson were handed stoppage-time red cards.
In France, Monaco stretched their winning run in Ligue 1 to seven matches as they earned a 2-1 victory over fellow Champions League chasers Marseille.
Aleksandr Golovin scored his third goal in four matches to give the hosts a second-half lead and Folarin Balogun's expert chip sealed victory as Monaco moved up to fifth, level on points with their fourth-placed opponents and within one of the top three.
Amine Gouiri's consolation was not enough to stop Marseille from suffering a second straight defeat as they missed the chance to move back into the Champions League places.
Lyon lost ground on the top three after they were held to a frustrating goalless draw by Angers which leaves them two points behind Lille in third place.
In LaLiga, Athletic Bilbao fell to their third defeat in their past four matches after they lost 2-0 to Getafe thanks to strikes from Luis Vazquez and Martin Satriano.
Sevilla's relegation fears continued to grow after they suffered a third successive defeat, losing 1-0 to rock-bottom Real Oviedo courtesy of Federico Vinas' first-half strike.
Sevilla had to play the second half with 10 men after Tanguy Nianzou was sent off, and they sit just two points above Elche who occupy the final relegation place.
Ilaix Moriba, Fer Lopez and Williot Swedberg were on target to boost Celta Vigo's European hopes with a 3-2 victory over Valencia.
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