In front of a crowd of 796 at Croft Park, Dave McTiernan broke the deadlock to give Spartans a 72nd minute lead.
Stan Mugisha looked to have salvaged a point for the mid-table Pics when he equalised a minute into stoppage time but to scenes of great celebration, Jarrett Rivers popped up with Blyth`s winner almost straight from the restart.
Nantwich`s hopes of catching Blyth meant they needed to win most of their remaining games and make use of their game in hand.
However, a 2-0 reverse at the Weaver Stadium against a Whitby side looking for a play-off spot themselves means the Dabbers have an awful lot to do and are looking for favours.
They got none from the Seasiders though as goals from Dave Carson in the very first minute of the match and then Dale Hopson after 64 minutes moved them up to sixth.
They are now level on points with another north east side Spennymoor Town, who were held at home by struggling Halesowen Town.
A crowd of 668 at the Brewery Field saw Cameron Steele give the Yeltz a 26th minute lead that Rob Ramshaw levelled 18 minutes from time. The point lifts Halesowen three points above the drop zone.
Stourbridge and Warrington Town are above the Moors in third and fourth place respectively.
Early goals in each half from Luke Shaw and Lee Shaw helped Grantham Town claim their third win of the current campaign over a floundering Glassboys side, whose Luke Benbow equalised in the 15th minute.
Having already won at the War Memorial Ground in the Integro League Cup in late January before defeating the Glassboys 2-1 at home last month, the Lincolnshire visitors collected a league 'double' over Gary Hackett’s men to maintain their own hopes for grabbing a play-off spot.
Warrington scraped a 1-0 Cantilever Park victory over Hednesford Town, courtesy of a 32nd minute Mitch Duggan effort.
Grantham are joined by Buxton, Matlock Town and Workington AFC on sixty-four points – three behind the top five.
Buxton hit the final nail in bottom side Skelmersdale United`s Premier Division coffin, hammering their young side 6-0 at Stormy Corner.
It was only 1-0 at the break after a 41st minute Jamie Green goal. But in the second half, Greg Young, Bradley Grayson, Joe McGee and a Liam Hardy brace made it 6-0 and First Division North football in all probability for Skem next season.
Matlock were comfortable 3-0 home winners over Ashton United in the end.
It was goalless at the break but then Michael Williams broke the deadlock just six minutes after the restart, Marcus Dinanga added a second on 71 minutes and Adam Yates sealed victory with a third in the 77th minute.
Workington were beaten 2-1 at Owen Street by a Coalville Town side who have now just about preserved their place in the Premier Division.
That was courtesy of an 18th minute Nathan Watson goal added to by Alex Dean`s 74th minute second – a Danny Jenno own goal in stoppage time all the Reds could muster in response.
With Skelmersdale down, who follows them out is looking likely to be Ilkeston FC and then two from Frickley Athletic, Sutton Coldfield Town, Corby Town, Halesowen, Marine AFC or Mickleover Sports, making it an exciting end of season with very few matches being non-events.
Two of those sides, Corby and Marine, shared a 0-0 draw at Steel Park in front of 538, while two more, Ilkeston and Frickley, met at the New Manor Ground with the Robins running out 1-0 winners, thanks to a goal right on half-time from Tevahn Tyrell.
Sutton Coldfield earned a good 2-1 Coles Lane victory over Barwell with goals from Michael Townsend after 52 minutes and then Max Wright two minutes from time – all after Callum Ball had given the Canaries the lead in first half injury-time.
Mickleover suffered a 3-1 home defeat to Stafford Rangers to keep them looking over their shoulders.
Tyler Blake gave Sports an early sixth minute lead but Izak Reid equalised five minutes later and Kieran Morris gave the R`s a 2-1 interval lead. Levi Reid wrapped up the points with the visitors` third nine minutes from time.
Follow us: @evostikleague on Twitter | Facebook www.facebook.com/evostikleague
Keep up-to-date with our exclusive email newsletters.
Subscribe