The Heinrich Malan-coached CD will have to exorcise a few demons against a side they lost the Super Smash T20 crown to when everything indicated they should have won it.
Many had understandably written off the visitors' limited-overs campaign in what appeared to be a hangover from the T20 disappointment but the William Young-captained side's character has instead come to the fore.
"We didn't have as many wins as we'd have liked but the thing about our team is there's a lot of self-belief that we've built up over campaigns so it was a just a matter of time before the lads got back into form.
"The thing about a campaign is once you have a few wins the momentum keeps snowballing and you feel like you'll keep going and winning."
A misfiring top order seems rejuvenated after a flushing of spark plugs to see the likes of Jesse Ryder, Young, Tom Bruce, Cleaver and Kieran Noema-Barnett join Mr Consistent George Worker with the bat although Joshua Clarkson has gone off the boil.
It boggles the mind what'll happen when everyone fires but he suspects those who haven't for the past few games believe they are due to deliver rather than they're out of form.
"The biggest thing's everyone hitting it well and in a good frame of mind so it's just a matter of getting out and putting it together in the park, really," says Cleaver.
But his role is pivotal on the field to a point where he sees things without even having to look, as it were, to the extent where one may well ask why aren't the padded ones captain?
"You try to notice things that other people don't so you try to relay them to the captain and try to help with field placements and all those sorts of things," he says, stressing wicketkeepers have enough on their plates without needing to assume the mantle of "strings-attached" captaincy before batting.
He points out only two captains ago ex-Black Cap Kruger van Wyk was a wicketkeeping skipper but, he clarifies, it's a bit like few glovemen who end up opening batting.
Cleaver, who can't be too far from national selectors' plottings but who can probably do with more batting crease time rather than rushing out to boost a total, tends to relish batting in the middle order after fielding because it gives him insight on pitch behaviour.
"Also switching on and switching off [while keeping] is the big thing."
He believes Wellington's experience brings out the best in the predominantly young Stags who are looking forward to testing themselves against the best.
The hosts will be without his counterpart, Luke Ronchi, returning from injury and going straight into coach Mike Hesson's equation for the touring South Africans.
CD will tomorrow sorely miss maiden century maker Bruce and new-ball, death-over seamer Ben Wheeler who Cleaver describes as "absolutely quality players who bring so much to the team" but going to the higher echelons of cricket with the team's blessings is an unwritten clause.
"It's going to be tough without those two but that just means other batters and bowlers wil have to step up to do the job and take it away," he says as the Stags are only two games away from a fairy-tale three consecutive crowns in the format to join a pretty exclusive boys' club who can claim to have done that in major association cricket.