'We must all make sure that Leo shines'
Messi and Argentina, who finished runners-up to Germany in Brazil in 2014, launch their Group D campaign against World Cup newcomers Iceland in Moscow on Saturday.
"I'm proud to be able to share this experience and am trying to be with him all the time. We hope we can perform every game by his side. We must all make sure that Leo shines."
Messi will be appearing at his fourth World Cup as he chases an international title that has so far eluded the five-time Ballon d'Or recipient.
"Leo is training very well, giving an example of how to prepare at training but likewise off the pitch as well," said Chelsea's Willy Caballero, who is likely to start in goal for Jorge Sampaoli's side.
"He's very tuned in. I'm surprised by how good he's looking and I hope he starts the tournament well because if he's on form that will help us all raise our game."
Messi won the Golden Ball award four years ago as the best player of the tournament but has scored just five World Cup goals in his career.
Argentina's other group stage opponents at this year's finals are Croatia and Nigeria.