Bielsa worked with Messi as Argentina coach.
"Messi is a completely proven player. And you know what Argentines do with people we admire? We subject them to a number of tests that nobody can pass, unless you are a world champion, like Diego Maradona," Bielsa said during a press conference.
"Messi will go through this process. We also show our affection with conjecture, putting in doubt everything we love and value."