Fleury took a knee to the head in Friday’s loss to the Red Wings. The NHL didn’t think the hit was severe enough to take him off the ice as part of its concussion protocol, but Fleury has a history of concussions.
Marchessault suffered a lower-body injury Friday. Both players are expected to miss at least a week.
The injuries come on the heels of the Golden Knights losing forward Erik Haula to a lower-body injury. He went on IR Saturday.
The Golden Knights take on the Bruins on Sunday afternoon, and Malcolm Subban, whom Vegas claimed on waivers from Boston during the offseason, will get the start in net.
Vegas also recalled goaltender Maxime Lagace and forward Alex Tuch from the AHL’s Chicago Wolves.
Fleury, 32, won three Stanley Cups with the Penguins before being selected by the Golden Knights in the expansion draft.