A series of missed chances and one disgraceful decision cost Spalding United.
There is no doubt that the Tulips should have extended their one-point advantage with a seventh successive league win.
Goals from Nathan Whitehead and Bradley Wells put them 2-0 up but Gresley could have made no complaints if they had gone 5-0 down.
Although ex-Holbeach United striker Courtney Meade pulled one back, Spalding looked in complete control.
However, at 2-1 going into the last minute, they were punished for failing to turn a dominant display into a big lead.
Referee David Hunt seemed to be too keen on being the centre of attention all afternoon.
Bizarrely, he pointed to the penalty spot for handball as Meade’s left-wing cross appeared to hit Neal Spafford on the shoulder.
Even if the ball hit his arm, it certainly would not have been deliberate.
A second bookable offence – the first yellow card was also controversial – meant that Spafford was sent off.
Pearson Mwanyongo kept his cool from 12 yards and the Moatmen could not believe their luck as both teams extended their unbeaten start to the league season.
Although Spalding have every right to blame the man in black, they must accept responsibility because this game should have been all over as a contest before the break.
Whitehead nodded home Jordan Lemon’s right-wing cross for a dream start.
Nathan Stainfield headed straight at keeper Robert Peet who then denied Andy Wright before Whitehead missed the target.
Wells’ far-post header was ruled out for offside and Peet pushed away his 20-yard drive then Stainfield’s header was cleared off the line by Michael Pearson.
Matt Varley volleyed over, Wells inexplicably failed to convert a close-range header and Wright fired too high at the end of another flowing move.
Wells maintained his run of scoring in every home game, slotting the ball through Peet’s legs from Wright’s pass.
Michael Duggan barely had a touch of the ball but he was beaten by Meade’s finish off the inside of the post.
Stainfield wasted another chance and Downey’s low shot was held by Peet.
But instead of securing the points, Spalding were left bewildered by that decision to award a penalty.
4-2-3-1: Duggan 6; Lemon 8, Spafford 8, Stainfield 8, Walker 8; Varley 8 (sub Cullingworth 82 mins), Whitehead 8; Acar 9 (sub Lockie 84 mins), Downey 8, Wright 8; Wells 8 (sub Longville-Daley 86 mins). Subs not used: Hamilton, Vince.
3-5-2: Peet; Carlisle, Roome, Wakeling; Mwanyongo, Harrison (sub Ford 63 mins), Pearson (sub Samba h-t), Harris (sub Brown h-t), Morris; Melbourne, Meade. Subs not used: Barrett, Walker.
Whitehead (3 mins, 1-0); Wells (60 mins, 2-0); Meade (68 mins, 2-1); Mwanyongo pen (89 mins, 2-2).
Spafford (second bookable offence).
Whitehead (persistent fouling); Downey (dive); Carlisle, Meade, Spafford (fouls).
Jenk Acar - constant threat down right wing.
Rugby Town (H) – Tuesday.