Lionel Messi is a doubt for Argentina's Copa America quarter-final tie against Ecuador, so says Lionel Scaloni.

With the holders having already booked their progression to the last eight, Messi, who is the record appearance maker at the Copa America, sat out Argentina's final Group A match against Peru.

His absence was not felt as Lautaro Martinez's double propelled Argentina to their third win of the tournament.

However, ahead of Thursday's knockout clash with Ecuador in Houston, Scaloni suggested the 37-year-old may miss out again.

"We will wait a few hours and make a decision. Another day is always better. We'll decide on the basis of the response we get today," Scaloni said on Wednesday.

"We'll try to get him to play and if he doesn't, we'll try to find the best thing for the team.

"I'm going to talk to him today, I think it's fair that he takes his time and trains as much as he can."

Should Messi not make it, then Scaloni will likely lean on the tournament's leading scorer Martinez, who has netted four goals so far despite starting only one match.

Regardless of Messi's fitness, Argentina, who beat Ecuador 1-0 in a pre-tournament friendly, are big favourites to progress to the semi-finals, with Opta's predictive model handing them a 68.4% chance of victory.

Yet Scaloni knows Ecuador must not be underestimated.

"Ecuador are a well-drilled side with good players and a good coach," he said.

"They are one of the best teams in the Copa America. They have a real chance of challenging for the title.

"Anyone can easily reach the final and compete with the best in the world.

"Yesterday's game between Colombia and Brazil was of a very high standard. Uruguay are also doing very well."

Argentina have won their last eight matches, including friendlies, equalling the longest winning streak under Scaloni.

A win over Ecuador will set a new record for La Albiceleste since Scaloni's debut as coach in September 2018.