Louis Briscoe's second half goal helped Mansfield claim three points at the R Costings Abbey Stadium as they came from behind to beat injury-hit Cambridge United.
U's manager Jez George handed a first start to January signing Andy Pugh, and saw his side take the lead in the sixth minute. Mustafa TIryaki was fouled on the edge of the box and James Jennings curled the resulting free kick around the wall and in at goalkeeper Alan Marriott's near post.
Unfortunately for United the lead lasted only two minutes. A Mansfield free kick on half-way was floated into the box, and Ross Dyer rose highest to guide a great header back across goal and into the far corner.
The rest of the half was a scrappy affair, with neither keeper tested. United suffered another blow when Ryan Jackson went down injured just before half-time. The AFC Wimbledon loanee was unable to continue, and was replaced at half-time by another debutant, James Brighton.
Mansfield started the second half well, and a spell of pressure resulted in Dyer feeding the ball to Briscoe, who did the rest with a powerful shot through Naisbitt and high into the net.
United battled gamely, but couldn't fashion a chance to grab an equaliser and had to reflect on a fourth successive league defeat.
Man of the Match: Andy Pugh. A lively full debut from the ex-Welling man.
FULL TIME: Cambridge United 1-2 Mansfield Town
21.36: That's full time, United couldn't create anything in those last few minutes, and Mansfield are worthy winners here at the R Costings Abbey Stadium
21.34: Another change for the Stags as we move into the last minute, it's Hutchinson for Green.
21.32: Long free kick into the box gets a flick off Hughes but Marriott (Alan) collects ahead of Marriott (Adam).
21.29: Gary Roberts blasts in a free kick from fully 30 yards which Naisbitt does brilliantly to parry. McAuley heads the resulting corner to safety. Double change for United, Hughes and Marriott on for Tiryaki and Eades.
21.27: Substitution for Mansfield, Rheed on in place of Meikle. The Stags sub puts the mountain in man mountain.
21.25: Yellow card. Jennings tripped by Meikle, that'll be a free kick to United and a booking for the Stags winger. United with the free kick wide on their left, Jennings with it and it's headed behind, goal kick.
21.22: Nothing much has happened for ten minutes. United working hard but look short of quality. A sloppy pass back from Pugh is intercepted by Roberts, who finds Green, but his shot is blasted over the bar with McAuley in close attendance.
21.12: Yellow card. Tiryaki's flick finds Pugh, who goes down under challenge from Riley. That's a free kick and a booking for Riley, not sure about that but whatever. Jennings opts to dink the free kick in rather than go for goal, and Mansfield head clear.
21.11: Bit of a lull since the goal, Mansfield understandably have backed off a bit and the U's dont' really have the knowhow to fashion much.
21.02: GOAL Cambridge United 1-2 Mansfield Town. It's been coming since half-time, United can't clear properly and the ball finds Dyer on the edge of the box, who works it wide to the left to Louis Briscoe who steps inside and blasts a shot which rather goes through Naisbitt's hands and into the roof of the net. Powerful effort from the winger, 2-1.
20.59: United spring forward down the right, Roberts to Eades who goes down under challenge from Sutton. Free kick is bent in under the bar by Jennings but Marriott makes a good punch to get it away.
20.58: Roberts works the ball on to Green in the U's box, but he can't quite make room for a shot and when he does Rory McAuley is there to block the ball and K.Roberts completes the clearance.
20.54: Quick break from Mansfield down their right with Meikle, who plays it to Green and his shot deflects away. Corner to the Stags. Geohagan wins the header but the ball curled straight out before coming back in, goal kick.
20.51: There's been a half-time change for United. Ryan Jackson, who spent a long period on the deck receiving treatment in the first half, is off, and James Brighton is on for his debut at left-midfield. Eades has switched to his more natural right side, more problems for Jez George.
20.49: We're about to restart here, United to kick off shooting towards the NRE.
HALF-TIME: Cambridge United 1-1 Mansfield Town
20.32: Eades dinks the free kick in and McAuley plants a header just wide. That's half-time, scrappy stuff but patched-up United can be pleased with their showing so far. Mansfield dangerous opponents, and Dyer is winning everything in the air, but United have had more chances to date. All set up nicely for part two.
20.31: Pugh does ever so well to win the ball on the right and set United off on a counter attack. Cross eventually comes in from the right, flicked on by Berry and Pugh loops an overhead kick onto the roof of the net. One minute to be added, which is bizarre given Jackson was down for at least two receiving treatment a few moments ago, Anyway, United will have a free kick to end the half as Shaw is stopped illegally 30 yards out.
20.24: This is pretty mediocre fare, neither side really grabbing the game by the scruff of the neck. Mansfield probably edging it on points, though on the evidence of tonight's match I don't think they're one of the five best teams in the division.
20.20: United corner after good work from Jackson and Roberts. Looks to be a shout for handball as the cross comes in, but it's away and Mansfield can break! Green charging forward, Mansfield have players over but the striker opts to go for goal himself and Roberts makes the block and it's away for a throw.
20.17: Big Exodus Geohagan plays for Mansfield these days. He's just dropped the ball onto the pitch as he lines up one of his long throws and been penalised for a foul throw. Bit harsh that.
20.16: United struggling to clear their lines at present, this is Mansfield's best spell of the match to date.
20.13: Ball worked on to Briscoe on the Mansfield right, but his shot is straight at Danny Naisbitt who grabs it at the second attempt.
20.07: Good play from Jennings, who has been all over the show for United so far, finding Shaw, who opts to shoot when Pugh is in space to his left and trundles a shot wide.
19.59: Can't work out whether that was a brilliant header or poor defending for their goal, doubt Jez George will be a happy chappy either way. Jackson motors forward but his attempted cross is blocked behind, and though the resulting corner causes mild panic in the Stags box the visitors clear.
19.57: GOAL Cambridge United 1-1 Mansfield Town. Out of nothing Mansfield are level. A long free kick from half way goes into the box, and Ross Dyer rises highest to head back across goal and into the far corner with Naisbitt and several defenders rooted to the spot. That goal was almost in slow motion, but it's all square.
19.55: Just what United needed, and Jackson stings Marriott's palms as the U's break forward again, the keeper just about hanging on as Pugh sniffs around. Mansfield then come forward and have a throw down in the corner, but the ball sneaks out for a goal kick.
19.53: GOAL Cambridge United 1-0 Mansfield Town. Tiryaki having his shirt pulled by Riley on the edge of the box, free kick United, just on the left edge of the D, good position for a shot from Eades or Jennings, who are both standing over it. It''s Jennings, and it's in. Round the wall and beating Marriott at his near post.
19.50: No real pattern to the match so far, United having more possession but yet to channel that towards the Mansfield box.
19.47: Here we go, United attacking the South Stand in this first half.
Cambridge United: Naisbitt, Roberts, Jennings, Hudson, McAuley, Jackson (Brighton 45), Eades (Marriott 85), Shaw, Berry, Pugh, Tiryaki (Hughes 85). Subs: Marriott, Hughes, Jarvis, Brighton.
Mansfield Town: Marriott, Riley, Sutton, Geohagan, Howell, Briscoe, O'Neil, Roberts, Meikle (Rheed 82), Green (Hutchinson 90), Dyer. Subs: Worthington, Stevenson, Rheed, Redmond, Hutchinson.
19.41: TEAM NEWS. One change for United, Andy Pugh comes in to partner Mustafa Tiryaki up front. Rossi Jarvis is the man to make way. United's injury problems are such that boss Jez George can only name four substitutes.
In contrast Mansfield can name a bench full of experience and a team to match, including top-scorer Matt Green, tricky winger Louis Briscoe, and the experienced but tempremental midfielder Gary Roberts, no relation to the Cambridge City boss of the same name (that I'm aware of).
19.40: Hello everyone and welcome to the R Costings Abbey Stadium for tonight's match, Cambridge United v Mansfield Town. A few technical difficulties have beset me this evening but we're up and running now and ready for what is a crucial match for both sides.
Reporting by Matt Gooding