The Lions now know they must gain victory at Alfreton Town on Saturday and hope one of AFC Telford United or Farsley Celtic do not win.
Both teams were playing for something with Spennymoor going for a play-off place, so it probably explained the edgy start by both teams.
The hosts’ Shaun Tuton who was making his return from injury had an early chance, but his shot lacked the required power to cause a real problem.
John Johnston then created a bit of space for himself and got a short on target, but again it lacked power.
Town’s Mark Anderson shot straight at Guiseley keeper Owen Mason and they should have scored with just over ten minutes to go, when Rob Ramshaw produced a powerful header, but Mason made a crucial save clawing the ball away.
Its importance was highlighted moments later, when the Lions, needing a win to stay up, got the vital breakthrough.
Felix, who has been a key player for the Lions in recent seasons, produced a low strike to send most of the 1,001 fans at Nethermoor Park wild and keep Guiseley’s hopes alive until the final day.
Caretaker assistant Luke Potter, said: “We are buzzing, the lads have given everything today, it was just about that bit of quality, we kept our shape and then Kaine has got through and produced a nice finish.”
Neighbours Farsley kept their hopes of beating the drop alive courtesy of a 1-1 draw at Darlington.
The Quakers took the lead through Tyrone O’Neill, but Kennedy Digie levelled for Celts with a bullet header in first-half stoppage time.
York City secured a play-off spot after goals from Lenell John-Lewis and Mitch Hancox saw off Fylde 2-1, while Scarborough Athletic are back in the division after a 2-1 home win over Warrington Town.
Michael Coulson (16) and Bailey Gooda (81) with the goals for Boro.
Bradford Park Avenue lost 4-0 at Chester.