The Chile international signed for the Blaugrana last season in a €26 million deal, but a series of fitness problems restricted him to 31 competitive starts in his first season at Camp Nou.
Together, Messi and Sanchez scored five of Barca's eight goals in Saturday's 8-0 friendly victory over Raja Casablanca in Tangier, and the Argentine says that it is time for the former Udinese ace to shine.
"Alexis has been with the team for a while," he told the club's official website. "Last season he had a bit of bad luck with injuries, but he will be an important player for Barca."
Despite the hefty scoreline against the Moroccan side, Messi stressed that the team is not yet at 100 per cent, while revealing his pleasure at being able to play the club's entire pre-season.
"We felt some fatigue tonight," he explained. "It was a bit hard for us, but it is normal during the pre-season.
"We are training well and improving physically. We hope to enter the season in the best possible way.
"I have not rested this much in a long time. I always arrive late in the pre-seasons and it is good that I will be here for the entirety of it. I think all will go well."
The Catalan giants will tackle Paris Saint-Germain, and former player Zlatan Ibrahimovic, in a pre-season friendly on August 4 after the Supercopa Catalunya was called off.