Spalding seem certain to finish bottom with two games to go – but they could still be saved from relegation.
If they win both matches with maximum points then Grimsby need five points from their last two to finish above them.
However, Spalding’s fate will all depend on the reports on Scunthorpe Town who are the only team wishing to be considered for promotion. If they don’t go up, the league will stay as it is.
Spalding play Boston next week, then Market Deeping on the last weekend, while Grimsby face Bourne and Boston.
On Saturday, Grantham’s Dan Freeman picked up seven Spalding wickets to bring his total for the season to 68.
The bottom side were bowled out for 119, but Grantham lost four wickets –three of them to Jonathan Miles – before claiming victory.
Boston scored their fourth successive win against third-placed Bourne – hitting 233-9 with Jonny Cheer and Fayadh Haffejee both making 53 and Colin Cheer taking five wickets.
Haffejee went on take three wickets as Bourne were bowled out for 95.
Market Deeping went on a run spree against Louth at London Road.
Jamie Morgan made the day’s only century with 108 and shared a fourth-wicket stand of 127 with James Hook (50) who then took the first two wickets. Louth were bowled out for 143.