PSG take on the Red Devils at Old Trafford on Tuesday before the return leg on March 6. Neymar will miss both games with a fractured metatarsal.
Per CNN's Becky Anderson and James Masters, Buffon said:
"I think this is a problem for us. I'm not sure if it's a big problem or a little one. I hope it's only a small problem and that we are nevertheless a team that can thrive without him, it would give us great strength and confidence.