Barcelona star Lionel Messi shied away from making major promises for the coming season Thursday, pledging only to do his "best" under new coach Ernesto Valverde.

Messi said he was not familiar with Valverde's style, but voiced cautious hope.

“We all start from scratch again. With a new manager, we don’t know how he works but we do know he is a great manager because of how he’s done in his previous jobs. He did very well at Valencia and then Bilbao.

"Well, I say the exact same thing I say all the time," he said at the team's celebration of a new sponsorship deal with Japanese e-commerce giant Rakuten at its Tokyo headquarters.

"Whenever I start a new season, there is a very clear-cut goal, which is FC Barcelona would do its best," said the Argentina international who recently extended his contract with the Catalan giants.

"Personally, I am very happy and looking forward to starting a new season," he said.

"Everything will become new (under Valverde). We are hearing a lot about his very good reputation," he said, adding that he held "hopes on the new beginning."

"We would like to do our best."

Teammate Arda Turan was more enthusiastic about the coming season.

"It's important that we are going to win all the titles this year. We can do it," the Turkey international said.

They were joined by Neymar and Gerard Pique for the media event with Rakuten founder and chief executive officer Hiroshi Mikitani.

Rakuten's four-year sponsorship deal, worth 55 million euros ($63 million) a year, will last through June 2021, with the option of a one-year extension.

The e-commerce firm replaced Qatar Airways, Barcelona's shirt sponsor since 2013.

Rakuten signed the deal as it seeks to expand overseas.

The company already owns J-League side Vissel Kobe and professional baseball team Rakuten Golden Eagles.