Lionel Messi insists he is ready to play the full 90 minutes of Argentina's last 16 tie against Mexico on Saturday.
The Barcelona forward made his first start since March in the goalless draw against the Netherlands on Wednesday after finally recovering from a thigh injury, but looked a long way short of full fitness.
Argentina coach Jose Pekerman must now decide whether to gamble on the 18-year-old's fitness improving or return him to the bench and recall either Hernan Crespo or Javier Saviola.
"Last night was not my best game and I didn't reach the standard I wanted to," admitted Messi.
"But it was more or less the first time I had played in three months and while I felt tired at the end, I do feel as though I am fit enough to get through the full 90 minutes now."
Nicolas Burdisso is almost certain to miss the game against Mexico because of a knee ligament injury, with Fabricio Coloccini set to take his place in the starting line-up.