Argentina coach Jose Pekerman is still not convinced Barcelona star Lionel Messi will be fit to feature at the World Cup finals.
The teenage maestro has not played since suffering a thigh injury in a Champions League game against Chelsea in March but hopes to return to action in Argentina's friendly against Angola on May 30.
However, Pekerman said: "It is hasty to say Messi will be able to play that friendly.
"Messi is getting back to his best form, but slowly. Obviously we hope he does. Day after day he is improving physically and that is restoring his confidence. We are still within the time frame."
One player almost certain to face the African side is Manchester United defender Gabriel Heinze.
The 28-year-old has not played a first-team game since sustaining a serious knee injury in a Champions League game against Villarreal in September, but was able to return to action with United's reserves in the closing weeks of the season.
Pekerman added: "We need him to have some minutes on the pitch - perhaps not the whole match, but some minutes.
"It will depend mainly on how he is in training, but we still want to see him play."
Both Messi and Heinze are certain starters for Argentina if fit, but doubts about their availability mean Pekerman has been unable to finalise his line-up for the Group C opener against Ivory Coast on June 10.
He added: "I know who most of the starters will be for the first game, but I cannot reveal them because we need to build up a plan to try to get to our best in a short period of time."