Agent Mino Raiola has some advice for Lionel Messi: Leave Barcelona to prove your greatness.

Messi has agreed a new deal with Barcelona but that contract remains unsigned amid uncertainty over the five-time Ballon d'Or winner's future at Camp Nou.

With the 30-year-old yet to put pen to paper, Manchester City – managed by former Barca boss Pep Guardiola – have emerged as a possible destination.

Raiola does not represent Messi but the Italy-born Dutchman – whose list of clients includes Paul Pogba, Romelu Lukaku, Marco Verratti, Henrikh Mkhitaryan and Zlatan Ibrahimovic – believes the time is right for a change.

"A player like Messi must try another experience with a different club and prove how great he is," Raiola said via Marca.

"Barcelona must be reinvented again."

Messi is Barcelona's all-time leading goalscorer, helping the Catalan giants to 29 trophies, including eight LaLiga titles and four Champions League crowns.

Raiola also shared his views on Neymar's world-record transfer to Paris Saint-Germain.

PSG activated Neymar's €222million release clause to lure the Brazil international from Barca earlier in August.

"The market, as such, no longer exists. Now it is countries who are signing players and that isn't football," Raiola added.

"But transfers of €200m are going to be normal from now on, it won't be crazy to see that."