Both sides picked up big victories to set up what could yet prove to be a title decider at Bretton Gate this weekend.
Finedon remain two points behind the table-toppers after they crushed Kislingbury Temperance by 164 runs at Avenue Road.
Batting first, the hosts declared on 285-5 after just 42 overs with opener Callum Berrill carrying his bat for 93 while John Bowers (73) and Drew Brierley (60) made the other eye-catching contributions.
In reply, only Rob Collins (28) made it past 20 as Kislingbury were skittled for 121 with Tom Brett (4-14) and Mark Wolstenholme (3-30) doing the bulk of the damage.
It was a similar story for the leaders as Nick Green (85), Sulaiman Saleem (74) and Chris Milner (64) scored well as Peterborough declared on 284-4 after 46 overs against Rushden & Higham Town.
And the hosts had no answer as they were bowled out for 129 with only Steve Materna (34) and William Bates (31) putting up any resistance against a visiting attack led by Mark Edwards (4-30) and Josh Smith (3-8).
Geddington lost ground on the top two after they went down to a 69-run defeat at Old Northamptonians.
Batting first, ONs were dismissed for 239 with Amrit Basra (77) and Richard Kaufman (41) the main run-getters while Chris Murdoch (3-44) and Tiaan Raubenheimer (3-50) were the pick of the Geddington bowlers.
However, they were unable to mount a meaningful challenge in reply with Patrick Harrington (35) and Raubenheimer (31) being two of only five batsmen who made it into double figures.
The visitors were all out for 170 as Kaufman (4-40) and Basra (3-35) rounded off fine all-round displays.
There was a big upset at The Meadow as hosts Brigstock thrashed Oundle Town by nine wickets.
Mark Hodgson (38) was the only batsman to make it past 20 for Oundle as they were skittled for just 79 as Mohammed Saif (5-22) and George Groenland (4-28) ran riot with the ball.
And the reply was straightforward as Suk Singh (25) and Groenland (31no) ensured the job was done in just 16 overs.
There was also a big win for Overstone Park as they thrashed Desborough Town by 174 runs.
Harry Gouldstone cracked 112 and James Sales struck 67 to help Overstone to a big total of 276-8, despite the efforts of Danyaal Malik (3-21).
Desborough’s reply lasted only 23.2 overs as they were bowled out for 102, Afaq Barbar (46) the only batsman to get going as Matthew Cannon (5-17) did the damage with the ball for the hosts.
While Peterborough and Finedon will do battle in a big game at the summit on Saturday, there is also a crucial clash at the other end of the table as third-from-bottom Desborough entertain Rushden & Higham, who sit at the foot.
Elsewhere, Geddington will bid to get back to winning ways when they entertain Brigstock while Oundle take on Overstone at Milton Road.
The other game sees Old Northamptonians hosting Kislingbury.
The big game of the day in the NCL Division One this weekend is at Harrington Road as first plays second.
Leaders Loddington & Mawsley are in control at the summit and will start the day 24 points clear of second-placed Burton Latimer in the race for the one promotion place.
Loddington maintained top spot with a 33-run success over Peterborough 2nd last weekend.
Ben Roughan struck 126 and Josh Plowright added 62 as ‘Loddo' put a big total of 270-6 on the board.
And, despite Balaji Ganesan making 93 in reply, Calum Plowright (4-46) and Nick Herbert (3-32) ensured the hosts were all out for 237.
Burton moved into second but are level on points with third-placed Wellingborough Town after beating them by three wickets at Hall Field.
Only Tom Howes (64) and Owen Morris (32) put up any resistance as Wellingborough were bowled out for 157 as Terry Butt (4-20) led a disciplined home attack.
In reply, Scott Sanders (31) and Charitha Kumarasinghe (31) gave Burton a solid start but wickets began to fall and it needed youngster Niall Ferry (28no) to see the hosts over the line on 159-7.
Wollaston and Brixworth are also in contention at the top end of the table but it was the former who took the honours when they met last weekend.
Paul Wilkinson struck 89 while Mark Ralph (42) and Lewis North-Row (43) also contributed as Wollaston reached 286-9.
And Brixworth were then undone by Chris Perry (4-38) and Callum Robertson (3-36) as they were bowled out for 143.