Ten-man AFC were comprehensively beaten by a strong Yorkshire Amateur, as they were served their first league defeat of the new year.
Club skipper Phil Buxton was dismissed early on in the tie by referee Majid Ali, before the Ammers fired home three second-half goals to round up a comfortable win.
The Bulls were dealt a cruel blow before the game even started, with defender Cameron Hough injured in the warm-up to add onto an already long injury list.
An even opening few minutes saw the hosts retain much of the possession whilst visiting AFC looked bright on the break, creating a promising opening on nine minutes when Tom Slone's teasing cross was headed over by Cameron Dear.
Down the other end the hosts were almost in front seven minutes later, as miscommunication between Matt Wilson and Hugo Warhurst allowed Adam Priestley to square across goal for Ashley Flynn, but Jack Harrison did superbly to clear the ball from the goal line.
Inevitably Bulls stopper Warhurst was going to be called into action, and he pulled out all the stops to keep out a one-on-one effort from Harrison Blakey.
Disaster then struck on 25 minutes, only moments after a promising spell of possession for the Bulls, as skipper Phil Buxton was dismissed with a straight red card for a challenge at half-way.
Backs were against the wall for the majority of the contest from thereon in, and centre-half Matt Wilson pulled off a miraculous recovery by prodding the ball away from the reach of Flynn from behind the striker deep inside his own penalty area.
With a man less and still an entire half to play, the Bulls fully well knew the task ahead of them, but it was made significantly harder when Harrison Blakey slotted home from close range with not even 40 second-half seconds played.
The one-way traffic continued at a steady flow, with Priestley firing wide from 15 yards before Flynn mistimed a first-time effort from a good position.
The second goal did eventually come, though, as Blakey secured his brace with a looping header which Hugo Warhurst was left disappointed not to have kept out.
AFC were far from giving up, and could have halved the deficit when Wilson volleyed Morgan James' header straight at Edward Wilczynski.
But the points were well and truly wrapped up for the Ammers with three minutes of normal time remaining, substitute Aiden Savory seeing his strike parried by Warhurst but into the far corner.
Matt Chatfield's side continued to battle for a goal back in a professional manner deep into injury time, but couldn't get on the score sheet as Brandon Webster curled high and wide from the edge of the Ammers penalty area after Gavin King led a late charge.
Final score | Yorkshire Amateur 3-0 AFC Mansfield
Scorers | Blakey (46', 67'), Savory (87')
Yorkshire Amateur XI | Wilczynski (GK), Smith, Serrant, Daly, Demsey (C), Field, Crawford, Blakey (Fogarty 76'), Flynn (Savory 71'), Priestley (St. Juste 79'), Sykes
Unused subs | Tiani, McLachan (GK)
Yellow cards | Sykes (45'+2), Daley (69'), Field (73')
Bulls XI | Warhurst (GK), Slone, Sketchley, Harrison, Wilson, McMillan, Walker, Buxton (C), Ryan (King 54'), James, Dear (Webster 70')
Unused subs | Warner, Matthews
Yellow cards | Ryan (34'), James (63')
Red cards | Buxton (25')
Man of the Match | Kian Sketchley