The reigning champion looked like it would have to settle for a point on a frustrating night at MetLife Stadium, having failed to turn its superiority into the game's opening goal.

But substitute Martinez, who also netted from the bench in his nation's opener against Canada, finally broke Chile's resolve when he lashed home two minutes from time.

It moved Lionel Scaloni's side on to six points at the Group A summit, three points ahead of Canada, which beat Peru 1-0 earlier in the day, meaning a draw against Peru in its final game will be enough to secure top spot.

Argentina dominated the first half with 13 unanswered shots, yet just three of those were on target. One of them saw Julian Alvarez fire straight at Claudio Bravo from close range in the 22nd minute.

Lionel Messi also went close to scoring in the 36th minute. La Albiceleste's skipper let fly with a fizzing 25-yard attempt that clipped the outside of Bravo's left post, while Erick Pulgar almost turned Nahuel Molina's cross beyond the Chile goalkeeper two minutes later.

La Roja had Bravo to thank for keeping Argentina at bay, as the reigning champion continued to carry the greater attacking threat after the break.

The veteran stopper beat away Molina's fierce strike within five minutes of the restart, and just after the hour mark, he produced a superb reflex save to tip Nicolas Gonzalez's drive onto the crossbar.

With the breakthrough still eluding the world champion, Scaloni bolstered his attack by introducing Angel Di Maria and Martinez for the final 17 minutes.

Chile had increased their own attacking threat by registering their first attempts on goal in the contest, with Rodrigo Echeverria calling Emiliano Martinez into action on both occasions.

Yet, there was to be a late twist in Argentina's favour when an 88th-minute corner broke kindly for Martinez, who reacted the quickest to fire into the roof of the net and send La Albiceleste through to the quarter-finals.

The recent history books would suggest Argentina should fancy its chances against Chile.

This is epitomised by the fact it is now unbeaten after 90 minutes in the past 13 meetings, winning eight of those, but that does not tell the full story.

Seven of those eight victories have only been by a single-goal margin and, of course, it lost on penalties in the Copa America final showdowns of 2015 and 2016.

Although it dominated most of this contest and registered 22 shots to its opponent's three, just the one goal was enough once more, with both of Martinez's strikes from the bench in this competition coming in the 88th minute.

Argentina progresses to the Copa America knockout stages for a 14th consecutive time, excluding when it withdrew from the 2001 tournament.

Chile looked set to frustrate Argentina once again at the Copa America, and hold out for a second successive clean sheet.

Its defensive resolve, along with an inspired performance by Bravo between the sticks, looked like it would remain firm and keep the reigning champion at bay, until Martinez's late intervention.

What will be more concerning for La Roja is the fact it has now gone four successive Copa America matches without scoring, while having to wait until the 72nd minute for its first attempt on goal today.

That is something it needs to address quickly ahead of its crucial final Group A clash with Canada, in which a victory could still see it snatch second place and a quarter-final spot.