Messi was expected to sign a new contract but financial complications at Barca left the forward no option but to leave, with Busquets now assuming the captaincy role.

Prior to Monday's  (AEST) Joan Gamper Trophy clash, the 33 year-old took the opportunity to reassure the Blaugrana faithful who were rocked by the news of Messi's departure, with the Argentina international set to join Paris Saint-Germain.

"We'll do it with you [the fans]," Busquets said at the Estadi Johan Cruyff. "We need you more than ever. We need your help, your support, and we're sure you'll give it to us."

Busquets, who led the tackles and interceptions charts at Barca last season while also completing the second most passes, joins an illustrious group of players to have captained the Catalan club.

Carles Puyol, Xavi and Messi all came before the midfielder and Busquets acknowledged he must now "meet the standards" set by those club legends in a role which he is "very proud" to take.

Having made his debut four years after the Argentina captain, the Spain midfielder was also quick to pay tribute to his former team-mate, with whom he enjoyed a 14-year spell with.

"I want to give a special mention to Leo," Busquets said. "Thank you, Leo, for taking Barca to the very pinnacle; for making history while being the best player in the world, and for beating all the individual and collective records [imaginable].

"We will always be very grateful for everything you have done. We will miss you and we wish you all the best."

While Messi, who netted 672 times in 778 appearances for the Spanish giant, edges closer to joining PSG, Barca begins its LaLiga campaign against Real Sociedad on 15 August as it begins the post-Messi era.