Saltburn took another step towards the championship with victory over Marske - but despite dismissing their opponents for 112 the leaders had to work for every run.
Chris Nichols, Richie Rennard and Rob Nicol kept them at bay and almost 41 overs elapsed before a four wicket victory was achieved.
Saltburn were grateful for 34 extras as Nicol claimed four of the wickets for 37 runs in 15 overs, seven of which were maidens.
Nicol top scored with 38 when Marske laboured through 46.2 overs for their low total.
Naz Singh delivered 23 overs, capturing three for 56, while Lee Hodgson's three victims were taken at a cost of 18 runs in 8.2 overs.
Although Guisborough also won they remain 33 points off the top.
They had 79 runs to spare at Normanby Hall where Paul Goodchild returned the outstanding figures of five for 16 in 12.3 overs and Richard Dunn assisted in the attack with figures of three for 39.
The Hall were all out for 109 after Guisborough posted 188 for seven. Graeme Murray (36), Imran Jan (41) and Dunn (34) were their leading scorers. Mohamed Zahid bowled throughout in the Hall attack returning four for 73 from 25 overs.
Billingham Synthonia remain bottom after losing their crucial match with Richmondshire by two runs.
Richmond improved their chances of staying up, but are still third from the basement.
Captain Andy Mollitt (48) and Shanoka Dissanayake (63) scored 111 of Richmond's total of 146 for nine. Keith Martin had a good day with the ball for Synners, returning five for 85 but his performance was eclipsed by Dissanayake.
His six victims cost 46 runs and when Christopher Layfield took three, Synners were all out for 144.
Brenton McDonald (34) and Keith Hewson (49) were the principal scorers and the only other player to make double figures in the match was Denis Wing.
Darlington were involved in a high-scoring game with Hartlepool at Park Drive.
Michael Gough and John Cannon both made half centuries in the Pool total of 256 for six. Neil Pratt (62) and Steve Chapman (32) gave Darlington's reply a good send-off but although Gary Moody added 46, the visitors were well short at 202 for seven. Gough picked up four of the wickets for 51 runs.
Alex Roberts was again in outstanding form in Middlesbrough's drawn game with Bishop Auckland at Kingsway. He batted throughout, hitting one six and 15 boundaries in an undefeated 108 made out of total of 156 for six. Phil Timmens bowled a hugely economical 18 overs, taking three for 23.
Ben Usher had a six and 10 fours out of 90 and Amul Mazumdar struck eight boundaries in 47 when Bishops batted first and reached 236 for four from their 50 overs.
Runs were scarce at Brinkburn Road where Darlington RA were all out in 41.2 overs for 83.
Neil Russell, Jason Robinson and Shaun McGarry shared the wickets for Redcar, who won by six wickets.
Martin Hood (31 not out) and Russell (38 not out) produced an unbroken partnership for the fifth wicket after four Redcar batsmen managed only 11 runs between them.
Northallerton are second from bottom after drawing at Great Ayton. Doug Mulholland and Jonathan Barnes both made half centuries in a total of 183 for seven with five of the wickets falling to Thara Gunnarathne for 55 runs.
David Grainge (66 not out) and Colin Murray, who scored 37 before being run out enabled Ayton to take their score to 154 for six at close of play.
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