Jenkins is set to face his former club at the Allianz Riviera stadium in Nice, a 32,600-capacity venue preferred to their usual Stade Felix Mayol home by Toulon for the crucial Pool Two clash.
Victory for Toulon could secure a quarter-final place one game inside the distance, but a Blues triumph would put them in the driving seat ahead of hosting Exeter in eight days' time.
"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."
Harlequins, despite losing their opening Pool Four games against Scarlets and Clermont Auvergne, can keep alive quarter-final hopes following back-to-back victories over Racing Metro if they topple last season's Heineken runners-up Clermont at the Twickenham Stoop on Saturday.
Clermont will arrive in London without France international flanker Julien Bonnaire, who has an arm injury, while Regan King, Morgan Parra, Lee Byrne and Thierry Lacrampe are also absent.
Elsewhere, Leicester head to Treviso in Pool Five knowing that only victory will be good enough to keep the heat on quarter-final rivals Ulster, and twice European champions Munster will win Pool Six if they claim a bonus-point success at Gloucester.
Despite losing heavily at home to Aviva Premiership leaders Saracens last time out, Gloucester will retain a quarter-final chance if they can floor the Irish heavyweights.
"We will have a real crack at Munster," Gloucester rugby director Nigel Davies said.
"Motivation won't be a problem for us. It is another big test, but we went out there (to Limerick) in October and gave them a game, and hopefully we can do the same at Kingsholm."
Sale Sharks, meanwhile, can take another stride towards the Amlin Challenge Cup quarter-finals if they beat Worcester on Friday night.
Last-eight spots are also the continued target for Bath, London Irish and Wasps on Saturday when they tackle Newport Gwent Dragons, Lusitanos and Bayonne, respectively.
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