Northants have not beaten Notts in any format since July 30, 2006 but will face the Outlaws in Saturday’s opening semi-final at Edgbaston (start 11am).
The winner of the match will take on Durham or Yorkshire, who clash in the other final-four tie, in the showpiece final at 6.45pm.
Northants lost to Notts in the T20 meeting at the County Ground just last month, but will hope to get revenge for all those years of pain by securing victory on Saturday.
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And head coach Ripley said: “We haven’t got a great record against Notts, so what better time to improve that record than on finals day when it really matters?
“I’m sure Notts will be favourites, and the rest of us will be trying to knock them over on the day.”
Northants slipped to an agonising one-wicket Royal London One Day Cup quarter-final defeat to Surrey on Thursday, but the focus quickly switches to finals day at Edgbaston, where Northants lost to Lancashire Lightning in the showpiece last season.
“We’ve been there before and we’re used to the routine,” Ripley said.
“We know the logistics of what we’re going to do, where we’re going to stay, what training time we’re going to get.
“That little bit of experience means there are no surprises, everyone knows what the arrangements are and I think that will be a slight advantage but it will be all about how we play on the day.”
The Steelbacks are struggling with injuries and unavailability, with pace bowler Richard Gleeson suffering a side strain during that last-ball defeat to Surrey and is unlikely to feature in Birmingham.
Sri Lankan Seekkuge Prasanna is also missing as he is on international duty, while Steven Crook is a doubt.
The all-rounder needed a runner while batting in the County Championship draw with Leicestershire earlier this week, and he missed the Surrey encounter.
Notts Outlaws have no such problems, and have been handed a boost with the news West Indies all-rounder Andre Russell has been given permission to play on finals day, after a brief stint at Trent Bridge in the group stages.
Notts also have the option of playing England pair Alex Hales and Stuart Broad.