Grimsby Town were narrowly beaten by Forest Green Rovers in a tight game at The New Lawn.
The Mariners controlled possession for long periods but rarely seriously tested home keeper Luke McGee.
And they were undone when Jake Young grabbed what proved to be the only goal of the game on 24 minutes as he finished a good attacking move.
James Hanson came in for his first start of the season as one of two changes to the Town side following the 1-1 weekend draw with Carlisle United.
Duncan Idehen was the other to come into the line-up as Harry Clifton and George Willliams made way.
James McKeown started in goal, with Mattie Pollock, Luke Waterfall and Idehen forming a three-man central defence as Luke Hendrie and Danny Preston operated as wing-backs.
James Morton and Terry Taylor were the midfielders, with James Tilley and Owen Windsor either side of Hanson in attack.
The substitutes were Ollie Battersby, Bilel Mohsni, Danny Rose, Luke Spokes, Montel Gibson, Matt Green and Virgil Gomis.
Forest Green's XI included former Mariners Elliott Whitehouse and Jamille Matt.
Waterfall had to make a clearance from a low cross as the hosts had the first attack of note, before Town looked to have been given an indirect free kick inside the Forest Green penalty area for a back-pass, only for the referee to reverse his decision and give a drop-ball.
McKeown made a block from Nicky Cadden, then Matt headed wide after meeting a chipped cross from Odin Bailey on the left.
A cross from Cadden on nine minutes was headed on towards Matt but Waterfall got the ball away for a corner, which was cleared.
A lengthy stoppage then came for home defender Chris Stokes to receive treatment after getting caught in the face by Windsor's boot as he stooped in an attempt to win the ball.
After a scrappy opening, Town began to come into the game but when the deadlock was broken, it was Forest Green who took the lead. Some neat build-up play around the box eventually led to Liam Kitching pulling the ball back for YOUNG, whose shot from 10 yards beat McKeown.
The home side had the ball in the net again two minutes later but the offside flag went up against Matt as he tapped in from close range after a scramble.
Forest Green were continuing to look dangerous as the half-hour mark passed and a corner on the right came off Waterfall and went out for another one, this time on the left. The delivery from the flag was headed clear, before a follow-up ball bounced through to McKeown.
Town had created few chances so far but Windsor did well to win possession on the right on 39 minutes and drive a low ball into the box, although nobody could get on the end of it and it went out for a goal kick.
A foul by Whitehouse on Tilley gave the Mariners a free-kick inside the Forest Green half but Taylor's ball from it was headed away. The visitors kept possession though and after the ball was worked back into the box, an effort from Windsor was blocked by Kitching.
As half-time loomed, Town were given a free kick in a central position, 25 yards from goal, when Tilley was brought down by Whitehouse. Tilley's shot from it went over the bar.
Three added minutes were played at the end of the half and a foul by Taylor on Odin Bailey gave the hosts a free kick on the right but they were unable to turn it into a goalscoring opportunity.
And with no further chances for either side, Forest Green went in at the break with a one-goal advantage.
No substitutions were made before the restart and an early foul by Preston gave the hosts the first opportunity of the second half to attack, although the free-kick was headed clear by Hendrie.
Carl Winchester was shown the first yellow card of the game after tripping Tilley as he tried to break through the middle.
Town's best chance of the game so far came on 51 minutes when a cross from Pollock on the right found its way through to Hanson and he gave the ball to Tilley, whose shot was saved by keeper McGee.
Goalscorer Young was replaced by Dan Sweeney as Forest Green made the first change on 54 minutes.
Soon afterwards, the hosts had a chance to double their lead when Winchester broke from the halfway line before finding Bailey on the edge of the box. His shot was saved by McKeown and the rebound from Bailey went wide.
A home free-kick from Cadden on the left was headed clear by Waterfall, before a double substitution by the Mariners saw Hanson and Idehen replaced by Gomis and Gibson.
A foul by Cadden on Hendrie gave Town a free kick near the right touchline on the hour but Taylor's low ball into the box went through to McGee.
Green came on in place of Windsor on 66 minutes in Town's final substitution, before Winchester fired harmlessly wide of McKeown's far post from 20 yards.
Scott Wagstaff tried his luck for the hosts with a curling shot from the edge of the box on 70 minutes but it was easy for the keeper, who made a comfortable catch.
At the other end, a cross from Hendrie was turned behind for a corner by Cadden but Morton's ball from the flag was headed away by Sweeney. Town kept possession though and Green eventually shot wide from 20 yards.
Cadden was replaced by Jayden Richardson with 16 minutes to go, then Gomis sent a weak shot through to McGee as the away side continued to look for an equaliser.
The last Forest Green change saw Josh March come on for Bailey, then Town's next attack ended when a looping cross from Tilley was caught by McGee.
A foul on Tilley by Whitehouse on 86 minutes gave the Mariners a free kick but Morton's ball from it had too much on it and sailed over the bar for a goal kick.
Town were still pushing forward and a cross from Hendrie on the left fell for Waterfall at the far post but his header was caught by the keeper.
A 25-yard effort from Hendrie was blocked as the clock ticked down, with the visitors given an additional three minutes to find a leveller.
A Town penalty appeal came as Taylor went down under a challenge inside the box but the referee ruled against the midfielder, showing him the yellow card for simulation and giving a free-kick to Forest Green.
Udoka Godwin-Malife was booked for time-wasting in the last of the added minutes but Town were unable to create any further chances and saw their hopes of taking a point from the game come to an end.
The Mariners are on the road again when they are next in action, as they travel to Stevenage on Saturday.
Forest Green Rovers
- Luke McGee
- Liam Kitching
- Chris Stokes
- Udoka Godwin-Malife
- Scott Wagstaff
- Nicky Cadden
- Elliott Whitehouse
- Odin Bailey
- Carl Winchester (C)
- Jake Young
- Jamille Matt
- Lewis Thomas
- Dominic Bernard
- Jayden Richardson
- Dan Sweeney
- Aaron Collins
- Josh March
- Matt Stevens
- James McKeown (C)
- Duncan Idehen
- Luke Waterfall
- Luke Hendrie
- James Tilley
- Danny Preston
- Matthew Pollock
- Terry Taylor
- James Hanson
- Owen Windsor
- James Morton
- Ollie Battersby
- Bilel Mohsni
- Danny Rose
- Luke Spokes
- Montel Gibson
- Virgil Gomis
- Matt Green
Referee: James Adcock
Next Up: Stevenage (A)