Victory would keep the Blues' hopes of reaching the knock-out stages alive and Jenkins believes Toulon's decision to move the match from Stade Mayol to Nice could work against them.
"The fact they have taken the game to Nice is good for us," Jenkins said. "I know how passionate and crazy their supporters are at Mayol.
"I am sure it will still be crazy in Nice, but it is a much bigger ground and it won't be Mayol.
"It's all or nothing for us. We have to put in a good performance out there, and we all know how big a task that is going to be.
"They will be eager to beat us after we turned them over at home (in October). They were gutted they lost in Cardiff. Having played at Toulon last year, I know how much they want to keep up their form in Europe and to retain the Heineken Cup."