On Tuesday evening, Barcelona confirmed that Messi had handed in a formal transfer request, signalling his intention to leave the club with immediate effect.
The 33-year-old's decision comes at a time where the club is going through a tumultuous period on the pitch and in the boardroom, and Bartomeu is facing increased pressure from the supporters to resign.
Following news of Messi's transfer request, mass protests were held across Barcelona calling for the beleaguered chief to step down, with many seeing him and his board as the root of the club's problems in recent seasons, according to the Evening Standard.
Bartomeu was placed under more pressure by former Barca captain Carles Puyol, who is the longest-serving captain in the club's history, after he took to Twitter to throw his support behind his former teammate.