The decision was met by a chorus of boos from supporters,
however, Stags boss Peter Shirtliff said the referee had made the correct decision to bring the players off early, telling the Mansfield CHAD Website "He said 'we're coming off to see what happens in the next five or 10 minutes'. I didn't think he had any choice but to do what he did."
The Stags had taken a deserved lead on the stroke of half-time through Richie Barker after some neat build-up play.
Simon Brown picked up the ball on the left hand side and found Hamshaw in space on the right-side of the box.
Hamshaw managed to cross it straight on the head of Barker, to head the ball into the roof of the net from just two yards.
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Nottingham Forest Official Website:
Abandoned (71 min) Mansfield Town 1 v 0 Nottingham Forest
Nottingham Forest's pre-season friendly with Nottinghamshire rivals Mansfield was abandoned after 72 minutes as a fierce thunder and lightning storm rocked Field Mill.
The Stags were leading 1-0 at that stage - thanks to a goal on the stroke of half-time from Richie Barker.
First half
Barker did his best to ruin Colin Calderwood's Mansfield return as he became the first man to breach the Nottingham Forest rearguard in pre-season.
Calderwood launched his career at Field Mill but it was anything but a happy 'homecoming' for the Forest boss as Barker opened the scoring on the stroke of half-time.
The experienced striker headed home from point blank range after good work from Simon Brown and Matthew Hamshaw - the first goal The Reds have conceded in 314 minutes of pre-season action.
Forest, who had drawn a frustrating blank against MK Dons on Wednesday, created openings in front of the Mansfield goal but were unable to find a way past veteran goalkeeper Carl Muggleton.
Nicky Southall came closest to a Forest goal when his header struck an upright, while Danny Cullip volleyed over the bar after the home side had only partially cleared a corner.
Gino Padula, looking to make the most of the opportunity to impress Calderwood, produced a superbly timed tackle to put the brakes on a quick break by Brown.
And the Argentinean followed that up with a goal-line clearance to deny the wily Barker.
Second half
Forest's hopes of salvaging a draw from their trip to North Nottinghamshire were dented - by a combination of Mansfield's dogged rearguard and the elements!
A fierce thunder storm over Field Mill prompted referee Graham Salisbury to bring the game to a premature end 18 minutes from time.
The Lancashire official was left with little alternative - despite howls of protest from a large proportion of the 5,000-plus crowd.
Forest, who introduced no fewer than 10 out-field players as substitutes at half-time (goalkeeper Paul Smith was the only survivor from the first half), struggled to create any clear-cut openings in the second half.
Grant Holt fired high and wide from a promising position, while Nathan Tyson drilled a low shot inches wide before the game ended ahead of schedule.
Forest: 1st Half Smith, Cullip, Bennett, Breckin, Padula, Southall, Clingan, Perch, Lester, Weir-Daley, Harris
Forest: 2nd Half Smith, Eaden, Fernadez, Thompson, Morgan, James, Gary Holt, Gardner, Bastians, Grant Holt, Tyson
Mansfield Town:
Scorer: Barker 44min
Referee: G.Salisbury
Attendance: 5,329 Away attn:2,104