Jon McCarthy and Ian Sharps masterminded a superb away victory – securing the Blues place in the National League for the 2016/17 season at Blundell Park this afternoon.
Second half goals from John Rooney and Ryan Astles confirmed the win – with Craig Disley’s goal nothing more than a consolation for the play-off placed Mariners.
Chester had the first half chance of the game, with Tom Shaw stabbing wide from Ryan Lloyd’s corner on three minutes.
But Grimsby were showing why they are in a comfortable play-off spot; Andy Monkhouse’s free header found the target – but Tony Thompson was equal to it with a solid one handed save.
The Blues weren’t letting the hosts have it all their own way though – and should have taken the lead on ten minutes.
Chapell’s scuffed shot was palmed away by McKeown, before Richards’ follow up was blocked on the line by a Grimsby defender.
It was an end-to-end opening; with National League leading scorer Padraig Amond firing over from Monkhouse’s cutback.
Amond was at the thick of it again moments later, somehow heading Evan Horwood’s cross wide of the near post.
Ben Heneghan then had to be quick to block Danny East’s effort inside the box; before Monkhouse volleyed wide during the home sides’ next attack.
Chester had soaked up all the first half pressure – and then took the lead on 48 minutes.
Chapell’s bursting run down the right and chipped cross was brought down by John Rooney – who cut inside and curled it home.
It was dreamland just after the hour mark – as the Blues doubled their lead.
Rooney was at it again, his superb inswinging free kick found Ryan Astles and the defender nodded home at the back post.
Grimsby were piling on the pressure to claw the game back – as Horwood whipped a free kick over the bar.
The hosts then were denied by a superb block up the other end from Shaw; before Alabi broke and his long range effort was excellently stopped by McKeown.
Ross Hannah – off the bench against his former club – had a chance to make it three but was denied.
Nevertheless, Grimsby halved the deficit on 83 minutes as – following a scramble inside the box – Craig Disley fired home.
The Mariners pressure was relentless, as Shaun Pearson nodded just wide from a corner; before Amond was found in behind the defence but skied his shot from 12 yards.
But the Blues hung on, securing their safety – and also a sensational victory in Cleethorpes.
GRIMSBY: McKeown, Tait, Pearson, Disley, Bogle (Pittman 71), Amond, Monkhouse (Jennings 70), Nsiala (Robertson 76), East, Nolan, Horwood.
SUBS NOT USED: Clay, Henderson.
CHESTER: Thompson, Higgins, Heneghan, Astles, Hunt, Chapell (George 89), Rooney, Shaw, Lloyd, Richards (Hannah 68), Alabi (Hobson 79).
SUBS NOT USED: Worsnop, Mahon.
SCORERS: Disley 83; Rooney 48, Astles 61.
REFEREE: Mr S Bennett.
ATTENDANCE: 4,575 (210 away).