Spalding suffered their fourth successive defeat – despite taking the lead early in the second half.
Gav Sharman outpaced the home defence out wide and ran in his second try of the afternoon to establish a well-deserved advantage.
However, Mansfield used their forwards more effectively to respond and take control.
Spalding kicked off with the notorious disadvantage of Mansfield’s sloping pitch and immediately the home team looked to pin the visitors down into their 22.
Richard Cooke and Ash Anker were constantly tackling any threat.
Having absorbed the early storm, scrum-half Will Shields was starting to snip around the tackle area and the link with Willis Ingleby at fly-half was working well.
Suddenly Spalding caught Mansfield out of position as the backs passed the ball along the line out to Sharman on the left wing.
With the try line beckoning, he was tackled but brilliant support play by Ingleby saw him pick the free ball up and dive over for the opening try.
In typical fashion Mansfield immediately responded from the restart – pinning Spalding down in the left-hand corner and their flanker broke down the blind side, evaded a couple of tackles and went over for a converted try.
A few minutes later and a crash ball move created a break through the middle of Spalding’s defence and the home team went over, followed by a successful penalty.
While tackling, George Brown took a knee to the head and Tom Wilson came off the bench for the rest of the game.
With half-time approaching, Mansfield were attacking deep into the left corner following a kick ahead. Fullback George Douglas looked to have the ball covered but with it breaking free, Ashton Capes held back the Mansfield attacker off the ball and was yellow-carded. Taking an attacking scrum the odds were in Mansfield favour.
Spalding’s scrum held heir own with props Jacob Greaves and Kev Hudson not giving an inch all afternoon.
With the ball won, Dan Adams broke through the middle. From the tackle area the movement continued with Spalding securing a scrum on Mansfield’s five-metre line.
A quick blind side move saw Sharman in and with an excellent conversion by Ingleby, the half-time whistle went with only three points separating the teams.
Within a couple of minutes of the restart and still a man down, Spalding shocked Mansfield with a storming break down the left by Sharman and with this try in the left corner Spalding had taken the lead.
Steadily Mansfield gained an upper hand led by their forwards grinding out territory but Spalding responded.
As Spalding mounted an attack, the ball was lost and a counter-attack saw a break-away try by Mansfield down the wing to restore a five-point advantage.
Pressure on Spalding mounted. Locks Luke Turner and Ash Piccaver made a series of tackles against waves of Mansfield driving forwards and the only relief for Spalding was some excellent runs in the centre by Adams but support runners were not with him.
Fin Peters came on for Capes for the final 10 minutes and with strange refereeing decisions against Spalding, Mansfield’s fly-half was kicking deep for touch.
After a succession of lineouts, Mansfield secured their fourth try in the final couple of minutes.
Spalding: Greaves, Barrett, Hudson, Turner, Piccaver, Anker, Cooke, H Brown, Shields, Ingleby, Sharman, Adams, G Brown, Capes, Douglas. Subs Wilson, Peters, Reid.