Previews: Marseille focused on title, not coach
Belgian Gerets, who took charge in September 2007, said on Wednesday he would not stay at Marseille because of the lack of trust between himself and club owner Robert Louis-Dreyfus.
"For us players, the most important thing right now is to be champions," captain Lorick Cana told Thursday's L'Equipe.
"As the team captain, I feel the players are not too disturbed going into the final sprint."
Although some players were shocked by Gerets's announcement, they would not let their personal feelings interfere.
"We are professionals. We heard it could disturb the team but it is part of our careers," said defender Ronald Zubar.
"If we become champions, it will be thanks to him (Gerets)."
Midfielder Mathieu Valbuena, who became a regular starter under Gerets, said he was "stunned" by the news the Belgian would leave.
However, he added Marseille would be fully focused on the job in hand, saying: "We will not let go, we will do everything we can to be crowned champions in May. There is nothing to be afraid of."
Victory against Toulouse at the Stade Velodrome would send Marseille five points clear for at least 24 hours. Bordeaux are at home to Sochaux on Sunday.
Seven-times champions Olympique Lyon, third six points behind Marseille, will be under pressure when they travel to Valenciennes on Saturday.
Anything other than a win could see fourth-placed Paris St Germain, a point behind, overtake them should they beat Stade Rennes at home on Sunday.
The top two teams in Ligue 1 will qualify for the Champions League group stage, with the third-placed team going into the third preliminary round.
A fourth-place finish would mean a UEFA Cup spot, and, for Lyon, a loss of 20 to 25 million euro.
At the other end of the standings, third from bottom St Etienne host Nancy and 17th-placed Nantes take on bottom club Le Havre, who will be relegated if Sochaux, 16th, do not lose at Bordeaux.