EAST RUTHERFORD, New Jersey  - Argentina coach Lionel Scaloni said he takes it game by game in deciding who starts up front at the Copa America after opting for Julian Alvarez over Lautaro Martinez to partner Lionel Messi for a second straight match.

With Argentina's all-time leading scorer Messi the first name on the team sheet for key games, there is significant competition in the squad for the position of second striker.

Scaloni has opted to start Alvarez in wins over Canada and Chile, with Serie A's top-scorer Martinez replacing him from the bench in the second half of both games.

Alvarez has scored one goal so far, while Martinez has netted twice, including Tuesday's late winner against Chile which sent Argentina into the quarter-finals.

"Lautaro and Julian have played together," Scaloni told reporters.

"There's always the need for balance. And, well, Lautaro is very happy today, and Julian is too. I will always choose the one that I think is best suited for that match.

"Today Julian played, but we have 11 players. We have to balance the game plan.

"Sometimes there might be a disruption of that balance for any reason, but usually, I like playing with a good structure. We will be making choices throughout the tournament (depending on the opponent)."

Scaloni added that sealing qualification for the knockout stages with a game to spare would allow him to experiment with the line-up in their final group stage match against Peru on Saturday.

Asked specifically about winger Alejandro Garnacho, who was an unused sub in both matches, Scaloni said: "We would love to see him because he is young and he is a fresh player.

"Sometimes we think that given the match, we could send him in. But then as the match evolves, we think maybe it is not the right match.

"Hopefully when we give them (young players) the opportunity, they will be able to seize it."

(Reporting by Aadi Nair in Bengaluru; Editing by Peter Rutherford )