FThe holders have done it the hard way to reach the final against Spain on July 19, with battling knockout stage wins over Cape Verde, Egypt and Switzerland - before Martinez's added time header saw them past the Three Loins.
As the clock ticked into the closing stages, Lionel Scaloni threw on the Inter Milan striker, just minutes before Enzo Fernandez's equaliser in Atlanta.
That changed the mood of the game and the 28-year-old made his mark to head home Lionel Messi's cross for goals off the bench in back-to-back games.
Martinez has been rotated out of the starting line up in the knockouts, with Scaloni opting for Julian Alvarez as Messi's partner, but he remains vital to the Argentinian cause.
At full-time he revealed what Messi told him to do after being brought on and how the plan paid off.
"People see the assists, the dribbles and the magic, but they don’t see what Leo does with his words. When I came on, he walked over and said, ‘Attack the space between the defenders. Go for the headers. Keep making those runs.
"We were 1-1 with less than five minutes to play. Leo looked at the scoreboard, then looked straight at me and nodded. He didn’t have to speak. I knew exactly what he wanted.
"Playing with him is incredible because he doesn’t only create chances with his feet. He creates belief in every player around him."