Lionel Messi's debut for FC Barcelona's first team did indeed occur on November 16, 2003, in a friendly match against FC Porto at the Estádio do Dragão. Messi was just 16 years old at the time.
Although this match was a friendly and not an official competitive fixture, it marked the beginning of Messi's illustrious career with Barcelona. He showcased his talent and potential during this match, impressing the coaching staff and fans alike.