PSG have picked up just three points from their last five matches to drop to ninth place in the Ligue 1 standings, seven points behind leaders Olympique Lyon.
PSG chairman Robin Leproux said the club was confident of turning their season around against Marseilles but insisted a loss would not spell disaster.
"We're not even considering losing at Marseille," he told the French daily newspaper Le Parisien. "We're going there to win.
"If we don't get the result we're hoping for, however, it will not be a reason to talk about a crisis."
Asked if Kombouare's job might be on the line, Leproux replied: "That"s a weird question. He has just arrived, showing real leadership and a true vision. He has everybody's backing at the club."
Marseille, who have rebounded from a slow start to be fifth, three points off the lead, received a timely boost ahead of the match when they beat Zurich 1-0 on Wednesday to keep alive their slim hopes of surviving the Champions League's group stage.
"It remains a special occasion with a special atmosphere and this ones gives us the perfect opportunity to bounce back," PSG striker Pegyu Luyindula told reporters.
PSG have often been toothless in their attack this season and face added problems in Marseille with forwards Mevlut Erding and Guillaume Hoarau both sidelined with injuries.
Lyon, who moved close to a berth in the knockout stages of the Champions League with a convincing 2-1 win at Liverpool on Tuesday, visit struggling Nice on Saturday.
Brazilian defender Cris, who was taken to hospital for checks after being unintentionally knocked in the head by Dirk Kuyt's knee at Anfield, has fully recovered and should play.
Surprise package Montpellier, second to Lyon on goal difference, face a tough test at Stade Rennes, also on Saturday.
Champions Girondins Bordeaux have lost their last two Ligue 1 matches to drop to third place a point adrift but showed signs of recovery by beating Bayern Munich 2-1 in the Champions League on Wednesday despite missing two spot kicks.
"Missing two penalties is not acceptable", coach Laurent Blanc told reporters ahead of Saturday's home game against Le Mans.
"That's something we'll have to work on in training. Set pieces are important."
