Chester-le-Street lost ground in the race for the three promotion places in Division Two when they conceded a 90th-minute winner to Hebburn Town’s Chris Smith.
Calvin McMahon fired past home goalkeeper Joe Clayton for Hebburn’s opener on 39 minutes and, after Chester’s Andrew Grant-Soulsby levelled following a corner, a draw looked the likely outcome – until Smith’s late clincher.
The Cestrians dropped back to fourth and Billingham Synthonia are now third – their highest position so far this season.
They dented Easington Colliery’s promotion hopes at the Welfare Ground, winning 2-1.
An early strike by Chris Dickinson was all that separated the teams until the 82nd minute when Macaulay Langstaff doubled Synners’ lead.
With only a couple of minutes remaining, Aidan Haywood threw the Colliers a lifeline – but Synners held on and are now only a point behind second-placed Ryhope CW.
Gary Pearson’s men made no mistake at Ryton and Crawcrook Albion, building up a five-goal advantage through Nathan O’Neill (2), Damien Stevens, Josh Home Jackson and Matty Weirs before Carl Piecha claimed a consolation goal.
South Shields have a six-point lead over Ryhope, who have a game in hand. The Mariners also went nap in their home game with Whickham, who failed to respond.
Lewis Teasdale, with a brace, Lee Paul Scroggins, Ibby Hassan and Warren Byrne were the marksmen.
Stokesley SC, beaten 4-0 at Team Northumbria, remain firmly rooted to the bottom of the table and Esh Winning occupy the other relegation spot after losing 4-2 to Willington.
After Lewis Martin and Corey Nicholson had fired the Hall Lane side two goals ahead, Esh levelled courtesy of Chris Goss and Liam Clark, but, late in the game, Willington took the points with further strikes from Adam Comby and William Preston.
l Morpeth Town will be the Northern League’s only representative in the FA Vase quarter-finals.
They defeated Berkhamsted 2-1 in Hertfordshire with goals by Luke Carr and Michael Chilton, after Tom Carter had headed the hosts into an early lead.
Morpeth will now be at home to Bristol Manor Farm, who defeated Sunderland RCA in the previous round, a week on Saturday.
Dunston UTS, who lifted the Vase in 2012, went out in their fifth round replay at home to Ashford United, who scored twice in the last few minutes through Michael Phillips and Dan Smith for a 3-2 win.
By the interval, Billy Irwin’s men led through Stephen Richardson and Malcolm Morien, but the referee’s decision to send off Stephen Goddard on 65 minutes proved decisive.
At that stage, the score was 2-1, with Shaun Welford having reduced the deficit, and, although UTS worked hard, their 10 men finally succumbed to the visitors’ pressure.