Guinness Premiership heavyweights Leicester and Sale Sharks will kick off the Millennium Stadium double-header - a game fallen English champions Sale must win to keep alive any hope of Heineken Cup qualification next term.
But the second semi-final could eclipse it for sheer raw aggression, especially after fall-out between the regions over Wales scrum-half Mike Phillips' lucrative transfer from Cardiff.
Phillips, who lines up opposite ex-All Blacks number nine Justin Marshall, will head to the Ospreys this summer in a six-figure switch.
And Ospreys team manager Jones, who previously held an identical role with the Blues, said: "There is an edge there.
"There is no getting away from it and no point trying to play it down, because there is a dislike and huge rivalry between the two regions.
"The Mike Phillips issue has just added a bit more spice."
Blues head coach David Young added: "'Grudge' is a word that seems to have been bandied about, but I would prefer to call it rivalry.
"I think whenever any of the Welsh regions meet you are going to get that, and the fact it is a semi-final adds to it.
"Mike's move to the Ospreys at the end of the season is high-profile and has had a lot of attention, but I know he will go out there and give it his best shot, as he has always done for Cardiff."
The Blues will be without Wales prop Gethin Jenkins, who suffered a shoulder injury in RBS 6 Nations combat against England last weekend, and Young said: "Although he does not require surgery, he will be out for two to three weeks.
"It is not the same injury that he has had in the past, and not as serious, and although he wanted to play on Saturday it is not possible."
Gavin Henson again misses out for the Ospreys as he continues his recovery from a knee problem, but James Hook will be back at the Millennium Stadium just a week after his fly-half masterclass left England floundering.
Sale, having slipped down the Premiership table to eighth, know Anglo-Welsh silverware represents a solitary remaining route into top-flight European competition next season.
Sharks rugby director Philippe Saint-Andre said: "This is a massive game for us, and a victory would give us the opportunity of playing at Twickenham in the final (on April 15) and the chance to earn a place in next season's Heineken Cup.
"We've had a bad run of injuries, but we have the majority of the team who won the Guinness Premiership title last May available again."
Sale smashed Leicester 45-20 at Twickenham 10 months ago to be crowned champions for the first time, and Tigers boss Pat Howard recalled: "The last time we played Sale in a cup game, I know who the better team was."
Leicester's preparations have been boosted by the return of their sizeable England contingent this week, but Ollie Smith, Martin Castrogiovanni and Leo Cullen are among confirmed non-starters through injuries.
England flanker Lewis Moody though, could be a surprise inclusion in Tigers' match-day squad.
Moody, who underwent shoulder surgery less than two months ago, missed England's entire RBS 6 Nations campaign, but his recovery is ahead of schedule and there is an outside chance he might be involved this weekend.