L'OM recorded a 1-0 win over the Turkish outfit in the Europa League on Thursday but fewer than 9,000 fans turned up to the 67,000 capacity Stade Velodrome.
The Marseille faithful opted to boycott the fixture following 6-1 and 3-1 losses to Monaco and Rennes respectively, after blasting the club's hierarchy for seemingly lying to fans and poor organisation.
Garcia, who himself has come in for criticism from supporters accusing him of maintaining a "cloud of smoke" with his "amateurism", hopes a resolution can be reached as he feels Marseille are a much stronger team with their fans behind them.
"We responded with a win, which is just what we needed," he said, as reported by the Ligue 1 website. "They players played the match in a somewhat unusual context, but managed to get the win. We need to prepare ourselves for Sunday's match. What's certain is that we're stronger when we're supported; it's up to us to make sure we win that match so our fans [who had largely boycotted the clash at the Stade Vélodrome] change their minds."