Elworth defeated NSSCL Division Four champions Newcastle & Hartshill to take a big step towards joining them in moving up.
Second-placed Elworth are 12.65 points ahead of Bagnall Norton, in third, while Porthill Park are a point further back.
Elworth managed to stick 151 all out on the board in the early stages of the afternoon as Mike Stewart made 46 and Matthew Yardley added 29.
Richard Parkes picked up 3-44 for the visitors, while Thomas Onions and Harry Ford shared four wickets.
Ryan Hall (33) and Parkes (29) led the Castle response, but they were bowled out for 139 as Tom Seabridge took 3-16 and Isaac Austin claimed 3-24.
Bagnall Norton ensured they will have a chance of promotion on the final day after winning at Moddershall & Oulton thirds.
It was a tale of contrasting half-centuries which powered Bagnall Norton to 220-7 from their 40 overs.
Daniel Gammon dropped anchor to make 77 not out, off 122 balls, hitting seven fours as he batted throughout the innings.
And Matthew Reynolds provided some late fireworks with a 34-ball 53 which featured four fours and four sixes.
James Mason was the pick of the Modd men’s attack, taking 4-48.
Elliott Massey (41) and 24 apiece from Kieran Griffin and Alex Andrews were the highlights in the home side’s chase.
But Brandon Missole’s 3-5 plus double strikes from Warren Aubrey and Cian Gibson, left Moddershall & Oulton all out for 135.
Porthill Park thirds swept to a nine-wicket win at relegated Meir Heath seconds.
Three wickets apiece from Max Blurton (3-18) and James Cope (3-27) dismissed Meir Heath for 104. Nick Maskrey top-scored with 40.
In reply, Will Price compiled 68 not out, with James Cope adding an unbeaten 22, to see Porthill Park home.
Stone SP thirds are also relegated after losing at Barlaston.
Sam Taylor’s 73 not out underpinned Barlaston’s 180-6 from their 40 overs.
Mat Morray chipped in with 40 and there were a couple of wickets apiece for Harry Tuckwell and Corey Jones.
Jones (29) top-scored after the interval, but Ethan Squire and Josh Williams captured 3-19 and 3-27 respectively to skittle Stone SP for 82.
Hem Heath thirds confirmed their safety with a nine-run win at Silverdale seconds. Usama Sajaad Dar’s 33 and 21 from Jack Wood helped Hem Heath to 128 all out. Gareth Metcalfe took 3-13
David Moors (59no) and Wayne Peach (34) did their best to get Silverdale over the line, but the home side closed on 119-4.
Bignall End were also away-day winners as they returned from Onneley with the points.
Andrew Howle (46) and Sajid Hussain (41) impressed as Bignall End amassed 159 all out. Mohammed Khalid took 4-22.
Jake Short’s 30 was the top score after tea, but Onneley were dismissed for 134 as Dharmaraj Ramanathan claimed 4-30.