An 89th-minute goal from Jon Froggatt was enough for Belper Town to beat Sutton Coldfield Town
1-0 and consolidate third place in Evo-Stik League Division One South.
A place in the play-offs is now looking almost assured for the Nailers, as they stretched their unbeaten run to a remarkable 18 matches in the league.
At the other end of the table, however, Mickleover Sports' plight became worse when they were thrashed 7-0 away to promotion-chasing King's Lynn.
Mickleover are at home to Belper on Monday.
It was also a bad day for Gresley. Joint manager Gary Norton had bemoaned their home form ahead of the game against Chasetown but the Moatmen could do nothing to improve it, crashing 4-1 to their visitors.
With Gresley 2-0 down, Michael Nottingham pulled one back with six minutes left.
But Gary Hay scored twice in the last minute to put Chasetown out of sight.
In the Evo-Stik Premier Division, Matlock Town's rearranged game away to AFC Fylde brought them only disappointment, as they went down 3-0.
However, Ilkeston were 3-1 home winners over Blyth Spartans, with goals from Aaron Hooton, James Reid and Gary Ricketts.
