The 34-year-old’s deal expired at midnight and despite months of rumour and conjecture, he has failed to commit to an extension.
Talks over a new contract are believed to be ongoing, meaning Messi may well decide to stay at the Nou Camp.
But, for now, the Argentine superstar is available for absolutely nothing.
Messi has been linked with moves to Paris St-Germain and Manchester City, where he would be reunited with his former boss at Barcelona Pep Guardiola, as well as America’s Major League Soccer.
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He is currently in Brazil playing for Argentina at the Copa America and became their most-capped player when he made his 148th international appearance against Bolivia on Tuesday, scoring twice and setting up another in a 4-1 win.