Defeats for bottom three Tranmere, Cheltenham and Hartlepool meant Stags’ midweek win over Tranmere had been enough after all as expected.
But the effects of that win left something of a hangover for Adam Murray’s men as they turned in a tired, lacklustre display at the Abbey Stadium and never looked like recovering from star man Sullay Kaikai’s first goal after only three minutes.
The man who knocked Stags out of the FA Cup earlier in the season bagged a first half brace and, although sub Rakish Bingham pulled one back, punishing a poor Josh Coulson backpass on 64 minutes, there was no be no comeback as Tom Elliott buried a free header near the end to seal United’s win.
Mansfield keeper Sasha Studer did not have the best of afternoons, twice beaten from outside the box despite getting his hands to the ball both times, the first from a 35 yard free kick.
But there were few performances of any great merit on the day as Stags lost for a sixth time in seven games and limp towards the end of the season.
The Mansfield side showed three changes. With Callum Elder missing out at left back with concussion, his place was taken by Lee Beevers, and Ricky Ravenhill took over the holding role in central midfield from Jamie McGuire.
Terry Hawkridge took over from Reggie Lambe on the wing as Lambe served a one-game ban for his dismissal on Tuesday night.
Mansfield fell behind after just three minutes with Studer beaten from a 35 yard free kick.
Kaikai took it from a central position, lifting it over the wall, and saw Studer fumble it over the line as he dived to his left.
Soon after Elliott shot goalwards from 18 yards, but it was straight at Studer.
Cambridge won a corner, but before it could be taken, midfielder Donaldson limped off with that looked like a hamstring strain and, after Oliver had headed clear, he was replaced by Taylor.
On 15 minutes the ambitious Kaikai tried his luck with another central free kick, this time from 40 yards, but it sailed wide.
Thomas was screaming at the referee after he felt he had been tackled from behind in the box, but play continued.
Thomas then did well to win the ball off Dunk, but his forward pass was just too hard for Oliver to reach before Dunn gathered.
However, on 31 minutes Thomas picked up his seventh booking in 10 games with a needless trip on Dunn in the middle of the pitch.
Oliver did well to battle for and win the ball on the right by-line and lift it onto the middle of the six yard box where Dunn beat Thomas to it.
Sutton hesitated before chasing a headed Raynes clearance which gave Dunk the chance to poke a half-volley wide from 25 yards.
Elliott tamely poked a sidefooted effort at Studer from 25 yards when he had enough time and space to give it more venom.
But United were 2-0 up on 43 minutes as Kaikai doubled his own tally.
The home side worked a short corner to Ball, who fed Kaikai just outside the box on the right. He looked up and zipped in a low shot which Studer got a hand to but was unable to prevent it finding the net inside his right hand post.
Looking for a hat-trick, a pumped-up Kaikai then made a run at Stags down the centre but, crowded out, left it to Elliott to curl one over the bar.
Tafazolli had to make a desperate clearance as Mansfield struggled to clear a scramble from a free kick, then Slew screwed a 20 yard effort well wide as Mansfield went in clearly second best after a poor half.
Desperately needing a spark, boss Adam Murray sent on Rhead and Bingham for Oliver and Hawkridge for the second half.
It wasn’t even a minute old before Ravenhill was booked for a foul on Champion.
Clements had a snap-shot blocked in a rare Mansfield threat.
Kaikai again fancied his hat-trick with a central free kick from 30 yards. He managed to get a powerful shot on target, but it was almost straight at Studer.
Mansfield had brief hope when Dunn failed to hold a Thomas cross at the far post, but there was no one close enough to make hay.
Dunn then confidently held onto a high Clements free kick under pressure.
United won another corner, taken short which saw Kaikai cross to the far post and Elliott guide a header narrowly wide.
Mansfield needed a break of some sort and got it on 64 minutes as Cambridge gifted them a way back into the contest.
Coulson’s under-hit back pass on the left sent Thomas scampering forward and, as Dunn came out to meet him, the youngster squared a pass to his left to leave Bingham an easy finish into the empty net.
A great run down the right by Bingham saw him beat his man and get in a cross from which Clements wanted too long to shoot, his effort eventually blocked.
As the home side then broke, he tried to trip Kaikai. By the time United had won a free kick near the corner flag, the referee came back to book Clements.
On 79 minutes Kaikai wasn’t too far wide from 20 yards. Then Elliott had a shot on the turn deflect wide for another home corner as Cambridge finished strongly. From that, Nelson put his header wide.
From a Studer clearance, Bingham produced a delightful headed flick, but Rhead’s powerful finish was well over on 84 minutes.
Elliott excited the home fans with a powerful run, that ended with a stinging, swerving shot at Studer, which the keeper held.
Any hopes Mansfield had of a draw they wouldn’t have deserved were extinguished on 88 minutes.
Elliott fed Dunn wide on the left, who tricked his way into space for a cross in front of goal where Elliott had been allowed the run of the box to plant a free header past a helpless Studer from six yards.
Bingham wasn’t far wide on the turn on the re-start.
CAMBRIDGE: Dunn, Ball, Coulson, Nelson, Dunk, Champion (Taylor 10), Morrissey, Donaldson, Kaikai, Slew (Bird 59), Elliott. Subs not used: Norris, Tait, Hunt, Mendez-Laing, Simpson.
STAGS: Studer; Sutton, Tafazolli, Raynes, Beevers; Ravenhill (Fitzpatrick 63), Clements, Thomas; Hawkridge (Bingham HT), Oliver (Rhead HT), Brown. Subs not used: Pidgeley, Hearn, McGuire, Marsden.
REFEREE: Kevin Wright of Cambridgeshire.
ATTENDANCE: 4,667 (274 away). CHAD STAGS MAN OF THE MATCH: Rakish Bingham.