AFC were left disappointed not to come away from West Yorkshire with a clean sheet after being downed by a late winner.
Hosts Pontefract Collieries, from a division above, eventually found a way past Hugo Warhurst despite a resilient performance at the back from the Bulls.
In a sixth pre-season friendly for Matt Chatfield's men, Ponte started the brighter side and had a firm grip on proceedings for the opening 20 minutes, yet Warhurst had little to do between the sticks bar a few simple saves.
The Bulls grew in confidence in the second half, although still struggling to beat the Ponte defence, and Ross Duggan came closest to an opener when he wriggled past two defenders before being denied by a clever block inside the penalty area.
Tensions grew in the second half between players on the pitch, boiling over when Morgan James clashed with Pontefract's Dom Claxton.
Claxton was shown a straight red card, whilst James too was dismissed for a second bookable offence.
With the tie at ten-a-side, Ponte and AFC both pushed for a winner; unfortunately for the Bulls, it fell the way of their hosts late on as Dan Keane finished off a slick move by tucking home into Warhurst's far bottom corner.
AFC move on to Tuesday night for their penultimate pre-season friendly, travelling to Harworth Colliery before returning home to host Swallownest on the eve of the new season.
Final score | Pontefract Collieries 1-0 AFC Mansfield
Scorers | Keane (90')