Argentina fly-half Juan Martin Hernandez expects to be fit for the potential Pool D decider against Ireland a week on Sunday.
Hernandez, whose conversion from full-back to fly-half at the World Cup has proved a major success, has been struggling with a thigh injury.
The Stade Francais star will miss Saturday’s clash with Namibia but is confident he will be ready to face Ireland.
“I can run but I can’t do sprints,” he said.
“Against Ireland I will be okay but I won’t take any risks so I won’t be playing on Saturday.
“I suffered a dead leg against Georgia but I’ve been having problems since the first match against France.”
Pumas skipper Agustin Pichot is a doubt for Namibia because of a hamstring problem.
“I don’t know if I’m going to play against Namibia),” he said.
“It depends on the coach’s decision. I’m quite calm because it’s not a new injury but a pain in the scar of an old tear.”