Paul Blackett's 25th goal of the season gave South Shields the edge over promotion-rivals Chester.
The Mariners travelled to the border city hoping to build on another away win at Buxton.
Chester were victorious when the two sides last met at the 1st Cloud Arena back in November.
Elliott Dickman made one change from the side that won in Derbyshire, with Dylan Stephenson returning to the starting 11 ahead of Aaron Martin.
Cal McIntyre kept his side that drew away at Scunthorpe unchanged.
Chester had the better chances of the first half but neither side managed to find the opening goal.
Tom Peers was on both sides of many Chester chances that would be denied by Myles Boney in the Shields goal.
Boney found himself under pressure in the 39th minute by two Chester players when the goalkeeper caught Charlie Caton in his attempted clearance, with both of the players requiring treatment for the collision and Caton being substituted.
Chester would hit the inside of the post from the resulting corner but Boney was able to claim the aftermath.
The division's top scorer Paul Blacket began to grow into the game after the interval with a plethora of attempts being denied by Wyll Stanway.
The Chester goalkeeper was accused of handballing the ball outside of the box by Shields players and supporters alike, but referee Matthew Scholes was not convinced.
Shields had a series of counter-attacks from Chester corners in the second half but Stanway was able to keep the Mariners at bay for most of the game.
Blackett eventually managed to get the better of Stanway in the 87th minute, as he made space for himself to get a shot off which rolled past the Chester goalkeeper to claim his 25th goal of the Vanarama National League North campaign.
Despite some threats from the Seals in injury time, Shields managed to hold on for all three points in a hard-fought fixture at the top of the table.
The result brings Chester to eighth and the Mariners to ninth, level on points with each other and two points adrift of the play-off spots.
Shields face Banbury United on Tuesday, where their game in hand over Curzon Ashton will be used.
South Shields: Boney, Clarke, Morse, Broadbent, Adams (C), Briggs, Smith, Jenkins, Heaney (Savage 78), Blackett, Stephenson (Martin 63)
Unused subs: Abbey, Gomes, Sloan
Goals: Blackett (87')