Who was the Barcelona manager when Messi made his first-team debut?

Frank Rijkaard was the Barcelona manager when Messi made his first-team debut.

Rijkaard, a former Netherlands international and AC Milan midfielder, coached Barcelona from 2003 to 2008. During his tenure, he helped establish a gifted young Messi within a senior squad that included stars such as Ronaldinho, Xavi, Samuel Eto'o and Deco.

Messi's first-team debut came in a friendly against Porto in November 2003, when he was 16. His official Barcelona debut followed in La Liga against Espanyol on 16 October 2004, at age 17. Both milestones occurred under Rijkaard, which is why the answer remains the same whether a quiz uses “first-team debut” to mean his initial senior appearance or his first competitive appearance.

Rijkaard also influenced Messi's early role. With Ronaldinho occupying the left side, he deployed Messi on the right, allowing the teenager to cut inside onto his stronger left foot. Messi scored his first senior goal in May 2005, also during Rijkaard's reign, and soon became one of Barcelona's defining players.