WATCH: Barcelona mark 15-year anniversary of Messi's first match

Lionel Messi was not always so cool and accomplished in front of goal, as Barcelona's video of his 2003 debut shows.

Barcelona have released footage of a pimply faced Lionel Messi's first minutes in senior football to mark the 15-year anniversary of his club debut.

Then just 16, Messi was introduced off the bench against Jose Mourinho's Porto in a friendly on November 16, 2003.

The match was organised to celebrate the opening of Estadio do Dragao ahead of Euro 2004 but has been remembered for the emergence of a budding superstar.

In the video, posted to social media on Friday, a young Messi admits to costing himself the chance of a brace through a combination of unselfishness and an uncharacteristically nervous first touch.

His team-mates in the 2-0 defeat included midfield great Xavi, long-serving defender Rafael Marquez and future Barca boss Luis Enrique.

Then-coach Frank Rijkaard made the teenager wait for his first competitive appearance, which came in October 2004 in a LaLiga win over rivals Espanyol.