Argentina forward Lionel Messi limped out of training on Wednesday after taking a heavy knock to his left foot.

The 18-year-old will have the injury assessed on Thursday morning to ascertain whether he will be available for selection for the Group C clash against Serbia & Montenegro in Gelsenkirchen on Friday.

The Barcelona star missed the last three months of the Spanish season because of a thigh injury and watched Argentina's World Cup opener against Ivory Coast from the bench after coach Jose Pekerman decided he was not ready for action.

However, Messi remains a key player in Pekerman's plans for the tournament and is likely to be named in the starting line-up as soon as the coach is convinced he is 100 per cent fit.