SPALDING United lost 4-2 to Market Drayton Town on Saturday, while Holbeach United were beaten 1-0 at Long Buckby.
In a thrilling Evo-Stik League First Division South tussle, the Tulips looked to have salvaged a point at one stage, having battled back from 2-0 down.
In poor first half Market Drayton hit the woodwork twice before Duncan Swan-Horler headed them in a deserved lead.
Tom Rogers looked to have made the game safe with a second on 46 minutes, but Gary Pawson (75) and Matt Kennedy (77) made it 2-2.
However, Drayton sub Jason Oswell struck twice in the last five minutes to hand the Tulips another defeat.
With Rainworth Miners Welfare beating Shepshed Dynamo 3-2, the Tulips are now 18 points from safety with just six games to go - and will be relegated next weekend should they fail to win at Kidsgrove Athletic.
In the UCL Premier Division, the Tigers suffered their second defeat of the week while Deeping Rangers were handed a shock 2-1 home reverse by Yaxley.
Elsewhere, it was a good weekend for Pinchbeck United in the Peterborough Premier Division.
Pete Roberts’ side won 4-1 at Oundle Town thanks to goals from Ian Dunn (2), skipper Bobby Patterson and Ryan Birtles.
They are now nine points behind leaders Uppingham Town - who drew 4-4 with Moulton Harrox - with four games in hand.
Joshua Ford (2), Danny Hussey and Joe Townsend got the Harrox goals.
See Tuesday’s Lincolnshire Free Press for more on the weekend’s football.