AC Milan's eighth Italian Super Cup trophy moves them equal with Inter Milan and behind Juventus who have won the tournament a record nine times.
Inter's skipper had not scored for his club since Nov. 3 in a 1-0 win over Venezia.
Reigning champions Inter came through what was supposed to be a tough test at the Stadio Olimpico with flying colours and are three points off the Scudetto pace with a game in hand.
Simone Inzaghi's side are provisionally ahead of Napoli after netting all five of their goals in the opening 45 minutes at the Stadio Bentegodi through a Marcus Thuram brace and further strikes from Joaquin Correa, Stefan de Vrij and Yann Bisseck.
Napoli coach Antonio Conte criticised the Video Assistant Referee (VAR) for not intervening to reverse a penalty that Inter Milan's Hakan Calhanoglu eventually missed in their 1-1 draw on Sunday.
The Italian champions remain undefeated in the competition this season and sit fifth on 10 points at the midway point of the new league phase format.
Inter are now in second place in the table with 24 points, one behind leaders Napoli, while Venezia are 18th.
Manager Thiago Motta acknowledged that Juventus are not in the Serie A title race just yet and emphasised the importance of maintaining focus on their growth after they secured a dramatic 4-4 draw with champions Inter Milan thanks to two late goals on Sunday.
Argentina striker Martinez lashed home his fourth goal of the season in all competitions on the hour mark after a poor clearance from Zeki Celik to give Inter a hard-fought win at the Stadio Olimpico in Rome.
Inter Milan stretched their lead at the top of Serie A to 10 points on Friday after cruising past sorry Salernitana 4-0 ahead of their Champions League clash with Atletico Madrid.
Juve's title hopes took a hit at the Allianz Stadium in Turin after Lautaro Giannetti poked home the only goal of the game in the 25th minute.
Marcus Thuram was key to Inter's win at a soaking Stadio Olimpico in Rome as, with his team trailing at half-time, the France attacker made it two goals each shortly after the break and forced the Angelino own goal which put Inter ahead in the 56th minute.
Simone Inzaghi's side prevailed in a tense but eventful clash at the San Siro thanks to Federico Gatti's own goal eight minutes before half-time
The Serie A title credentials of Inter Milan and Juventus will be on the line on Sunday as two giants of Italian football face off in a San Siro showdown.
Argentina forward Martinez glanced home the decisive goal in the 14th minute of an action-packed contest in Florence in which Nicolas Gonzalez wasted a late penalty for the hosts, who had Inter on the back foot for much of the game.
Inter Milan will face Napoli in the Italian Super Cup final after comfortably beating Lazio 3-0 in Friday's clash in Riyadh.
Doubles from Hakan Calhanoglu and Lautaro Martinez and a late strike from Marcus Thuram extended Inter's advantage on Juventus, who host Sassuolo on Tuesday night.
Italy midfielder Frattesi rammed home the decisive strike in the third minute of stoppage time of an incredible match at the San Siro full of late drama.
Adrien Rabiot's second-half goal earned Juventus a 1-0 home win over AS Roma on Saturday that took them within two points of Serie A leaders Inter Milan.
