Lionel Messi says he could struggle should he be called upon to face Ecuador on Tuesday.
The Argentina international featured for just over half an hour of the CONMEBOL game against Colombia, but warned afterwards he may be incapable of playing what would be his second game in a week.
"I felt good, but what with [having played] little football and not knowing how the [injured] leg was going to respond, I don't want to take chances," Messi told a post match press conference.
The Barcelona star also expressed concern that his problems could be compounded by having to play at a great altitude, something that is unavoidable given the location of Ecuador's stadium.
He added: "To play at a high altitude is really tiring, it will be a hard game and I come without many minutes."
Messi also addressed the game against Colombia, which finished 0-0, arguing that despite having "many chances to score," Argentina was "somewhat handicapped" by poor refereeing decisions.
Argentina leads the CONMEBOL table, five points ahead of second-placed Colombia.