Neal Trotman’s last-gasp header earned Plymouth Argyle all three points at One Call Stadium.
The defender rose highest to guide home Conor Hourihane’s free-kick deep into stoppage-time, which earned The Pilgrims an important away win.
Boss Paul Cox made five changes to his starting xi, with John McCombe, Ritchie Sutton and George Pilkington, who was recalled from Forest Green Rovers earlier in the day, forming a flat back three.
Behind them, Liam Mitchell replaced Alan Marriott between the sticks for his Football League debut, whilst Ben Hutchinson was preferred to Ollie Palmer in attack.
The Stags lined up in a 3-4-1-2 formation and began at a very high tempo, but were unable to create any chances with three corners in the opening five minutes.
Another Mansfield corner came to pass as The Pilgrims were pressed back by their determined counterparts, and barely able to break out of their own half.
Eventually, the hosts created their first opportunity on 13 minutes, and were unfortunate not to take a deserved lead.
In a move of free-flowing football, which saw Matt Rhead and Lee Beevers cut the Plymouth defence wide open, the latter delivered an inviting right-wing ball towards the near-post.
Sam Clucas latched onto the cross and turned the ball goalwards at almost point-blank range, yet somehow Luke McCormick produced a magnificent reaction save to keep his side level.
The Stags continued to look thoroughly menacing and a Rhead flick on from a long ball forwards, almost released Clucas, but Maxime Blanchard made a vital interception.
Plymouth’s first sight of goal came when Mitchell spilled a low left-sided cross by Jamie Reckord, but Pilkington was alert and cleared the subsequent danger.
Clucas blazed a long distance drive high and wide on 25 minutes following a fine pass by Jack Blake, as the slick Stags continued to dictate play.
Blake was an instrumental figure in the next Mansfield attack, as he burst into the area to capitalise on a loose ball after Rhead saw a shot blocked, and did enough to win a corner.
From Hutchinson’s deep-floated resulting delivery, Beevers headed the ball goalwards towards Clucas, who two yards out and with his back to goal, could only head over.
Hutchinson tested the resilience of The Pilgrims’ backline with another deep set-piece cross into the area on 33 minutes, but Plymouth again held firm.
John Sheridan’s struggling side enjoyed a rare chance two minutes later, when Romuald Boco’s header across the six-yard box found the lurking Lewis Allesandra, who headed over.
Hutchinson then became the first player to go into the referee’s notebook when he was penalised for a tackle on Blanchard on 36 minutes.
Despite their dominance, The Stags’ frustrations grew as Rhead headed over following another set-piece delivery by Hutchinson, just a few moments later.
Plymouth then enjoyed a short spell of possession prior to half-time, and almost created a clear-cut opportunity, when Reuben Reid, Allesandra and Boco linked up on the edge of the area.
Boco attempted to put Reckford into a one-on-one, but his poor touch allowed the ball to drift away from him, and alleviated the danger for The Stags.
In the final minute of an intriguing first 45 minutes, Rhead was off-target yet again from yet another Hutchinson cross, whilst at the other end, Mitchell held a low cross by Conor Hourihane.
The Pilgrims, now attacking towards their supporters in the North Stand, looked rejuvenated after the break, and almost opened the scoring within a minute of the re-start.
After latching onto Hourihane’s through ball, Reid turned away from McCombe on the edge of the six-yard box, but saw his powerful right-foot shot saved by Mitchell.
Two Argyle corners then came to nothing, and it wasn’t long before Mansfield regained the momentum.
Colin Daniel should have done much better when he latched onto Rhead’s stabbed ball towards the back-post, but sliced his effort horribly away from the target.
And a minute later, Rhead wrestled away from his marker to latch on to a long set-piece ball by Hutchinson, but saw his goal-bound header plucked out the air by McCormick.
The Stags were again on the front-foot by this stage, with Hutchinson providing constant danger to the Argyle defence with his teasing deliveries into the area.
On 55 minutes, the frontman was again the provider for Ritchie Sutton, who rose high above everyone else, but just couldn’t direct his header between the posts.
At the other end, Plymouth created a rare opening as Reid hit a tame 20-yard drive straight at Mitchell, following a quickly taken throw-in by Reckord.
Mansfield spurned a dangerous set-piece opportunity on the hour mark, when Daniel drilled a 30-yard drive high over the target and into the Quarry Lane End.
Rhead was also unable to test McCormick when he latched onto a deep right-sided cross by Beevers and headed well wide, midway through the second period.
Meanwhile, Plymouth skipper Hourihane caught a glimpse of goal at the other end, but swung a speculative ‘hit and hope’ effort, high, wide, and into the North Stand.
Stags’ youngster Blake received a yellow card for a strong challenge on Reckord midway inside The Pilgrims half on 69 minutes, as Mansfield looked the more threatening side.
Having not scored in over five hours of football, the hosts made an attacking change in their bid to earn all three points, as Calvin Andrew replaced Rhead for the final 20 minutes.
Andrew was unlucky to be flagged offside when he attempted to latch onto a piercing low ball by Blake, before The Stags made another change when Palmer was introduced for Clucas.
Plymouth created a dangerous opening with 81 minutes played, when Allesandra swung a low pass towards an accelerating Reid, which forced McCombe into a last-ditch tackle.
Argyle players and fans alike appealed in vain for a spot-kick, whilst the relieved Stags managed to scramble away the danger.
Both teams then made their final substitutions with Lindon Meikle replacing Hutchinson for The Stags, whilst The Pilgrims introduced both Paul Hayes and Tyler Harvey.
Mansfield almost snatched a victory with just a few minutes remaining, when Daniel picked up a loose ball on the edge of the area and hit a venomous shot straight at McCormick.
Daniel was almost the provider for Meikle on the brink of stoppage-time, as he skipped away from his marker on the left-flank and delivered a goalmouth cross, just too high for Meikle.
Trotman headed over from Hourihane’s long ball forwards as the match entered four minutes of additional time, with The Stags looking the more likely side to find the net.
However, in the 93rd minute, disaster struck as Argyle snatched victory.
Trotman again rose highest to reach Hourihane’s centrally-positioned free-kick and just got enough direction on his header to direct it beyond Mitchell.
The ‘Green Army’ faithful in the stand behind the goal roared emphatically, as they knew their side had recorded an important three points.
Attendance: 3,379 (460 away supporters).