Representatives of the Ligue 1 club tested the water with the Hoops during last weekend’s visit to Glasgow for their friendly with Rangers. Celtic value the 21-year-old Frenchman at significantly more than £20m and will not sell him before the end of the Champions League qualifiers. But Marseille’s interest could give Parkhead chiefs the opportunity to spark an auction with other suitors in England and Italy such as Everton and AC Milan. Although Celtic don’t need to sell Dembele – and the player himself has not been angling for a move – there is a growing feeling that a departure before the transfer window closes on August 31 is inevitable. Dembele started his career in France with PSG before moving to Fulham and then on to Celtic last year for a £500,000 development fee. Now the man who scored 32 goals in 49 outings for the treble winners could be ready for a return home. Already on the fringes of the French national team, Dembele is desperate to make the breakthrough at full level and a move to Marseille would help his cause.