Heslerton and Ebberston dealt out the shock results, beating pace-setters Staxton and Beckett League Premier Division champs Staithes in their respective clashes.
Staxton were bowled out for just 122 by Heslerton in a tight two-wicket win.
Jodie Robson (36) top-scored for the batting side, while Scott Brennan bagged 4-36, Adam Spoaven claimed 3-24 and Dan Jaminson picked up 3-37.
In reply, scores in the 20s from Brennan, Sam Triffitt, Tom Benthall, Paul Bowes guided Heslerton over the winning line, though figures of 3-30 from Andy Holtby kept them on their toes.
Ebberston stunned Staithes in their meeting by just 21 runs.
Ben Lealman's 63, Jonny Mason's 51 and Alex Machen's 25 carried Ebberston to 159, Chris Morrison (4-44), Paul Theaker (3-41) and Tom Steyert (3-41) causing the issues.
Richard Hegarty ploughed something of a lone furrow in the response with an unbeaten 70, due to the wickets of Ian Atkinson with 5-26 and Lealman with 2-33.
Forge Valley trimmed the gap on the leaders with a two-wicket success against Scalby.
Paul Hesp's 4-24 and 3-30 from Sam Fox held back Valley to 134-8, with Tom Brough's 73 being the major contribution.
C Rankin (41) and Jon barton (25) almost kept Scalby on the right path, but Chaarlie Tindall's five-wicket haul closed down their innings.
Ben Luntley was the start of the show for Cloughton as they beat Seamer by 26 runs.
Luntley dropped agonisingly short of the ton on 84, linked with Ricky Nock's 69 as Cloughton closed on 212-6, Gert Visser taking four of the wickets to fall.
Gary Jordan then took control with 5-24, while Jon King claimed 2-63, though Craig Baker's 62, Anthony Jenkinson's 32 and Dave Graham's 27 made things interesting.
Cayton leapt away from trouble with a win by 34 runs against basement boys Nawton Grange.
Dan Walker was unbeaten on 60, with Adam Robertshaw, Jake McAleese and Steve McAleese also hitting the 20s in Cayton's 179-6, George Bentley claimed 3-31.
James Greenlay did his best to keep Grange on the right path with 71, but Tom Sixsmith took 5-30 and Harry Holden 3-47 to deny them.
Mulgrave maintained their charge at the top of Division One with a win by 158 runs against a stunned Wykeham.
Andy Wood struck 106 and Joe Hinchliffe 56 to carry Mulgrave to 256. Adam Eustace picked up three of the wickets, while Dave Pearson Matt Vincent and Dan Peel claimed two.
Pearson completed a good all-round day with 36 in Wykeham's reply, but his efforts were in vain thanks to Craig Thompson's 5-22, Mark Jakson's 2-11 and Andy Thompson's 2-12.
Flixton 2nds are their closest rivals after a five-wicket win against Brompton.
Karl Theobald hit 48, while Mike Thompson and Simon Oble were undefeated in the 20s to push Brompton towards 172-7.
Luke Smith bagged 3-13 and then went on to top-score for Flixton with 51 not out. James Clark added 31, Geoff Hill 26 and Jake Hatton 26 as the retort had too much for Brompton.
Sherburn showed their power with a 138-run success against Bridlington 2nds.
Ben Simpson (77), Phil Pickard (33), Jamie Thomson (28), Kev Lickes (27) and Craig Sanderson (26) led Sherburn to 229-8, with Luke Beckett, Tom McMeeken and Matty Clay all taking two wickets.
Andy Leeson's 32 gave Brid a glimmer of hope, but three wickets each for Daley Wharton, Jack Pickard and Sam Appleton curtailed the innings.
Wold Newton won a low scoring affair against Thornton Dale by 46 runs.
Newton looked in a dodgy position, as they were bowled out for 112 by Sam Asquith (5-21), Charles Gray posting an unbeaten 37.
Matthew Todd was the only Dale batter to find any form though with 22, as James Knaggs (5-16) tore through.