Grimsby are fourth in the Blue Square Bet Premier after a Tom Naylor goal bagged three points at New Lawn.
The defender scored his first goal since joining on loan from Derby last month, poking in from six yards after Sam Russell spilt Andi Thanoj's cross.
Forest Green's best chance fell to Chris Stokes in first-half injury time when he struck the post from 12 yards.
Rovers have not scored in their last four games which has seen them drop from third to sixth in the table.
VIEWS FROM THE DRESSING ROOM
Forest Green Rovers manager Dave Hockaday told BBC Gloucestershire:
"It sums up our micro-season of the last four or five games.
"It's now a given that box-to-box we are as good as anything. It's now fine-tuning what's going on in the box.
"We had two or three chances in the first half and we didn't take them.
"Our keeper, who has been brilliant, made one mistake and they scored the goal. This is where they've got to learn."
Grimsby Town joint-manager Paul Hurst told BBC Radio Humberside:
"It is a good three points against a team that's up there challenging, playing good football, but I think with the exception of them hitting the post we have limited them to very very little.
"Our game-plan panned out how I hoped it would - after watching them on Saturday, I thought the longer the game goes they get a little frustrated and we'd have options to get the ball wide.
"That was the first test in some people's eyes in terms of against a promotion rival and we passed that one with flying colours and we quickly move on to another against Kidderminster on Saturday.
"One of the best things I can say is that I haven't really noticed him [Tom Naylor] - I thought he slotted in there as though he had been with us all season. He looked very comfortable and very assured."
Live Text Commentary
Full Time The final whistle is blown by the referee.90:00 +2:46
Andi Thanoj produces a right-footed shot from just outside the box that misses to the right of the target.90:00 +1:37
Chris Stokes concedes a free kick for a foul on Andy Cook. Direct free kick taken by Craig Disley.88:24
Corner from the right by-line taken by Joe Colbeck, save made by Sam Russell.87:12
The ball is sent over by Yemi Odubade, clearance made by Ian Miller.86:59
Free kick awarded for a foul by Lenell John-Lewis on Eddie Oshodi. Chris Stokes takes the direct free kick.85:48
The ball is delivered by Yan Klukowski, clearance by Sam Hatton.83:51 Substitution
Substitution Sam Hatton comes on in place of Aswad Thomas.81:51
Direct free kick taken by Sam Russell.81:51 Substitution
Substitution Ben Wright is brought on as a substitute for Matt Taylor.81:51 Booking
Booking Craig Disley receives a yellow card.81:51 Booking
Booking Matt Taylor booked for unsporting behaviour.81:47
Foul by Craig Disley on Matt Taylor, free kick awarded.80:32
A cross is delivered by Chris Stokes, Tom Naylor makes a clearance.76:39 Substitution
Substitution Yemi Odubade comes on in place of Al Bangura.75:23
The ball is crossed by Matt Taylor, clearance made by Andi Thanoj.73:37
Assist on the goal came from Andi Thanoj.73:37 Goal scored
Goal! - Tom Naylor - Forest Grn 0 - 1 Grimsby Tom Naylor grabs a goal from close range low into the middle of the goal. Forest Green 0-1 Grimsby.73:20
The ball is sent over by Andy Cook, clearance by Eddie Oshodi.73:10
Joe Colbeck produces a cross.
Corner taken by Joe Colbeck from the right by-line to the near post, clearance made by Chris Stokes.72:29
Lenell John-Lewis sends in a cross, blocked by Eddie Oshodi.70:28
Craig Disley produces a cross, save by Sam Russell.70:09
Joe Colbeck delivers the ball, Jared Hodgkiss makes a clearance.68:30 Substitution
Substitution Kieron Forbes comes on in place of Lee Fowler.68:30
Shot from just outside the area by Craig Disley misses to the right of the target.68:18
The ball is swung over by Marcus Marshall.67:39
Al Bangura crosses the ball, Andy Cook makes a clearance.66:31
The free kick is delivered right-footed by Lee Fowler from right channel, clearance by Bradley Wood.66:31 Booking
Booking Aswad Thomas shown a yellow card.66:24
Free kick awarded for an unfair challenge on James Norwood by Aswad Thomas.63:40 Substitution
Substitution Richard Brodie goes off and Lenell John-Lewis comes on.63:15
Andy Cook takes a shot. Save made by Sam Russell.62:54
The ball is delivered by Chris Stokes, clearance made by Ian Miller.60:45
Matt Taylor challenges Ian Miller unfairly and gives away a free kick. Direct free kick taken by James McKeown.59:21
Foul by Jared Hodgkiss on Aswad Thomas, free kick awarded. Joe Colbeck sends in a cross, Shot from deep inside the area by Ian Miller clears the crossbar.58:05
Yan Klukowski takes a shot. Blocked by Ian Miller.57:31
Magno Vieira produces a cross, clearance by Bradley Wood.56:43
The ball is swung over by Bradley Wood, Jamie Turley makes a clearance. Shot from 12 yards by Aswad Thomas. Save made by Sam Russell.55:03
A cross is delivered by Matt Taylor, clearance made by Bradley Wood.54:00
Craig Disley sends in a cross, clearance made by Eddie Oshodi.53:18
Centre by Magno Vieira, clearance made by Andi Thanoj.52:00
Effort on goal by Lee Fowler from just outside the penalty area goes harmlessly over the target.51:40
Corner taken by Yan Klukowski from the right by-line, clearance made by Andy Cook.51:29
Centre by Lee Fowler, Bradley Wood makes a clearance.51:05
Short corner taken by Yan Klukowski from the right by-line.50:29
The assistant referee signals for offside against Andy Cook. Sam Russell takes the indirect free kick.49:32
Al Bangura crosses the ball, Bradley Wood manages to make a clearance.48:31
Free kick awarded for a foul by Aswad Thomas on Matt Taylor. Lee Fowler delivers the ball from the free kick right-footed from right channel, clearance by Aswad Thomas.47:21
Unfair challenge on Craig Disley by Matt Taylor results in a free kick. James McKeown takes the free kick.45:01
The match restarts for the second half.45:00 +2:58 Half time
Half Time The whistle is blown to end the first half.45:00 +2:01
Foul by Tom Naylor on Yan Klukowski, free kick awarded. Yan Klukowski has a direct shot on goal from the free kick, save made by James McKeown.45:00 +0:17
Unfair challenge on Tom Naylor by Jamie Turley results in a free kick. James McKeown restarts play with the free kick.44:49
Ian Miller challenges Matt Taylor unfairly and gives away a free kick. Sam Russell takes the direct free kick.44:25
Chris Stokes concedes a free kick for a foul on Joe Colbeck. James McKeown takes the free kick.43:58
Chris Stokes produces a left-footed shot from deep inside the penalty area and strikes the post.42:57
Tom Naylor gives away a free kick for an unfair challenge on Matt Taylor. Lee Fowler takes the direct free kick.42:11
The official flags Richard Brodie offside. Sam Russell takes the indirect free kick.41:28
Marcus Marshall delivers the ball, save made by Sam Russell.40:18
James Norwood has a curled shot. Save by James McKeown.37:31
Foul by James Norwood on Bradley Wood, free kick awarded. Free kick taken by James McKeown.36:40
Bradley Wood challenges James Norwood unfairly and gives away a free kick. Yan Klukowski delivers the ball from the free kick right-footed from left wing, clearance by Andi Thanoj.36:16
The ball is delivered by Joe Colbeck, Sam Russell makes a comfortable save.35:46
Yan Klukowski takes a shot. Save made by James McKeown.34:59
Jamie Turley produces a cross.32:55
Lee Fowler takes a shot from just outside the penalty area clears the crossbar.32:26
Corner taken right-footed by Yan Klukowski from the left by-line, clearance made by Ian Miller.32:16
A cross is delivered by James Norwood, blocked by Ian Miller.32:09
Jared Hodgkiss produces a cross, Ian Miller makes a clearance.31:05
The ball is crossed by Joe Colbeck, Sam Russell makes a fantastic save.29:18
Bradley Wood sends in a cross, save made by Sam Russell.28:22 Substitution
Substitution Andi Thanoj is brought on as a substitute for Derek Niven.26:46
Magno Vieira has an effort at goal from the edge of the box that misses to the right of the target.25:59
Foul by Jared Hodgkiss on Andy Cook, free kick awarded. James McKeown takes the free kick.25:36
The ball is delivered by Bradley Wood, clearance by Jared Hodgkiss.25:03
Eddie Oshodi concedes a free kick for a foul on Andy Cook. Craig Disley takes the free kick.22:17
The official flags Richard Brodie offside. Indirect free kick taken by Sam Russell.21:55
Free kick awarded for a foul by Andy Cook on Eddie Oshodi. Eddie Oshodi restarts play with the free kick.20:18
Free kick awarded for a foul by Craig Disley on James Norwood. Yan Klukowski produces a shot on goal direct from the free kick.19:11
Foul by Al Bangura on Andy Cook, free kick awarded. Free kick crossed by Bradley Wood, save made by Sam Russell.18:28
Centre by Chris Stokes.15:33
Sam Russell takes the free kick.15:33 Booking
Booking Booking for Richard Brodie.15:29
Richard Brodie challenges Chris Stokes unfairly and gives away a free kick.13:57
Foul by Jamie Turley on Marcus Marshall, free kick awarded. Richard Brodie has an effort direct from the free kick, Jamie Turley gets a block in.13:44
Al Bangura takes the chance to get an effort at goal. Ian Miller gets a block in.12:17
Joe Colbeck takes a inswinging corner from the left by-line played to the near post, clearance made by Jared Hodgkiss.12:07
Aswad Thomas sends in a cross, save made by Sam Russell.11:09
Lee Fowler has shot on goal from just outside the area which goes wide of the right-hand upright.10:04
The assistant referee flags for offside against Richard Brodie. Sam Russell restarts play with the free kick.7:54
The ball is swung over by Lee Fowler, Bradley Wood makes a clearance.7:06
Free kick awarded for a foul by Craig Disley on James Norwood. Direct free kick taken by Chris Stokes.5:43
A cross is delivered by Lee Fowler, save by James McKeown.5:27
Free kick awarded for an unfair challenge on Magno Vieira by Derek Niven. Yan Klukowski restarts play with the free kick.4:44
Centre by Chris Stokes, clearance by Aswad Thomas.4:02
Al Bangura fouled by Richard Brodie, the ref awards a free kick. Direct free kick taken by Sam Russell.2:34
Centre by Marcus Marshall, clearance made by Chris Stokes.0:00
The match has kicked off.
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