Should he decide the Nou Camp is his next destination, Messi believes the prolific striker's signature will help Barca's bid to reclaim their former mantle as Europe's top team from Real Madrid.
There's still a week to go [before the World Cup].
Argentina superstar Lionel Messi has admitted that Frenchman Antoine Griezmann will be of great advantage for Barcelona if the club signs him this summer. I think that we will know my future this week.
But with Barcelona in the hunt, Messi has told his club to get the transfer over the line - or risk not winning the Champions League.
Griezmann, 27, continues to be linked with a move to LaLiga champions Barcelona after another fine season at Atletico.
They claim Atletico conducted a campaign to keep hold of Griezmann, including manager Diego Simeone, the players and staff.
The Argentina talisman said: "I am in agreement that to win the Champions League again we need to have the best players". The deal, should he sign, will make him the club's highest paid player; and the entire club has been endorsing the deal since it was offered - from the president right down to the kit man. It depends on the technical secretary and coach. "And he is very good!"
"That made the elimination even more painful and it was viewed as being even worse because of how it happened".