Alfreton dented Cambridge's hopes of a play-off place with a convincing win at the Abbey Stadium.
Liam Hughes hit the post for Cambridge just before half-time.
But Leigh Franks broke the deadlock as he headed home Josh Law's cross from close range early in the second half to send the visitors on their way.
Nathan Arnold's 20-yard strike doubled the lead shortly before full-time and Paul Clayton got a third in stoppage time with a close-range finish.
VIEW FROM THE DRESSING ROOM
Alfreton Town manager Nicky Law:
"The fans were brilliant. They never stopped supporting the team from start to finish and the players have shown their appreciation and gratitude at the end by going 60 to 70 yards to applaud them for their great efforts.
"I just wish the small band of moaners at our home games - who seem to criticise every little thing that goes wrong - would realise what a negative effect they sometimes have on players and get behind us instead. We could achieve so much more if we are all together.
"It is a sad state of affairs that we would rather play away from home where there is less pressure to perform."
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Live Text Commentary
Full Time The referee ends the match.90:00 +2:42
The assist for the goal came from Danny Meadows.90:00 +2:42 Goal scored
Goal! - Paul Clayton - Cambridge 0 - 3 Alfreton A goal is scored by Paul Clayton from close range low into the middle of the goal. Cambridge Utd 0-3 Alfreton Town.90:00 +1:22
Unfair challenge on Paul Clayton by Kevin Roberts results in a free kick. Nathan Arnold takes the free kick.89:49
Paul Clayton fouled by Josh Coulson, the ref awards a free kick. Leigh Franks restarts play with the free kick.88:14 Goal scored
Goal! - Nathan Arnold - Cambridge 0 - 2 Alfreton Goal scored by Nathan Arnold from just outside the penalty area to the top right corner of the goal. Cambridge Utd 0-2 Alfreton Town.87:28
Close range headed effort by Rory McAuley goes wide of the left-hand post.86:57
Corner taken right-footed by Tom Shaw.85:39
Paul Clayton challenges Tom Shaw unfairly and gives away a free kick. Direct free kick taken by Craig Ross.82:20
Effort from outside the penalty box by Nathan Arnold goes wide right of the target.81:53
Tom Shaw challenges Nathan Arnold unfairly and gives away a free kick. Josh Law restarts play with the free kick.80:46
Danny Meadows takes a shot. Craig Ross makes a save. Josh Law takes a outswinging corner from the right by-line played to the near post.80:15
Centre by Kevin Roberts, save by Phil Barnes.79:21 Substitution
Substitution Blaine Hudson replaces Jamie Reed.74:29
Free kick awarded for an unfair challenge on Theo Streete by Liam Hughes. Leigh Franks restarts play with the free kick.71:07
The ball is crossed by Rory McAuley, save by Phil Barnes.70:25
Unfair challenge on Michael Gash by Leigh Franks results in a free kick. Tom Shaw restarts play with the free kick.68:41
Luke Berry concedes a free kick for a foul on Paul Clayton. Free kick crossed right-footed by Josh Law, clearance by Kevin Roberts.67:01
Inswinging corner taken by Tom Shaw from the left by-line, free kick awarded for a foul by Josh Coulson on Paul Clayton. Direct free kick taken by Phil Barnes.66:12 Substitution
Substitution James Brighton replaces Charlie Wassmer.
Theo Streete gives away a free kick for an unfair challenge on Tom Shaw. Direct free kick taken by Kevin Roberts.58:31
Jamie Reed fouled by Darran Kempson, the ref awards a free kick. Kevin Roberts takes the free kick.57:57 Substitution
Substitution Tom Shaw is brought on as a substitute for Rossi Jarvis.53:59
Shot by Dan Bradley. Save by Craig Ross.53:17
Michael Gash is ruled offside. Free kick taken by Phil Barnes.51:11
Assist by Josh Law.51:11 Goal scored
Goal! - Leigh Franks - Cambridge 0 - 1 Alfreton Leigh Franks scores a headed goal from close in. Cambridge Utd 0-1 Alfreton Town.50:45
Corner taken right-footed by Josh Law from the left by-line to the near post,49:26
The assistant referee flags for offside against Jamie Reed. Phil Barnes takes the indirect free kick.48:27
The ball is sent over by Joe Anderson, Darran Kempson makes a clearance. Inswinging corner taken from the left by-line by Rossi Jarvis, Jamie Reed takes the chance to get an effort at goal. Phil Barnes makes a save.48:02
Shot from 18 yards from Paul Clayton. Save by Craig Ross.46:30
Shot by Steven Hewitt. Save by Craig Ross.45:01
The referee gets the second half underway.45:00 +1:05 Half time
Half Time The match has reached half-time.45:00 +0:22
Kevin Roberts produces a cross, Phil Barnes makes a save.43:26
Luke Berry fouled by Theo Streete, the ref awards a free kick. Joe Anderson crosses the ball from the free kick left-footed from left wing.40:55
Liam Hughes produces a drilled left-footed shot from just inside the area and strikes the post. Luke Berry takes a shot from just inside the penalty box which clears the crossbar.40:08
Jamie Reed takes a shot from 18 yards. Save by Phil Barnes.37:56
Luke Berry has an effort at goal from outside the box which goes wide left of the goal.35:42
Free kick awarded for a foul by Darran Kempson on Jamie Reed. Free kick crossed right-footed by Rossi Jarvis, clearance made by Leigh Franks.32:07
Danny Meadows is caught offside. Free kick taken by Craig Ross.29:33
Free kick crossed left-footed by Joe Anderson.29:33 Booking
Booking Darran Kempson is shown a yellow card for unsporting behaviour.29:23
Foul by Darran Kempson on Jamie Reed, free kick awarded.28:12
The referee blows for offside. Phil Barnes restarts play with the free kick.26:55
Inswinging corner taken by Rossi Jarvis, Dan Bradley manages to make a clearance.24:43
Long range shot from Dan Bradley misses to the left of the goal.24:22
Outswinging corner taken by Josh Law from the right by-line.23:45
Kevin Roberts concedes a free kick for a foul on Paul Clayton. Free kick taken by Dan Bradley.21:56
Free kick awarded for an unfair challenge on Michael Gash by Leigh Franks. Free kick taken by Rossi Jarvis.18:34
The ball is sent over by Jamie Reed, Header by Liam Hughes from deep inside the penalty area misses to the left of the goal.17:26
Inswinging corner taken right-footed by Rossi Jarvis from the left by-line, Effort from deep inside the area by Jamie Reed misses to the right of the target.16:53
A cross is delivered by Josh Law.16:14
Unfair challenge on Leigh Franks by Jamie Reed results in a free kick. Phil Barnes takes the direct free kick.15:43
Danny Meadows is ruled offside. Free kick taken by Craig Ross.14:14
Jamie Reed crosses the ball, clearance by Darran Kempson. Effort from the edge of the area by Luke Berry goes wide of the left-hand upright.13:11
Nathan Arnold has an effort at goal from close in which goes wide right of the goal.11:25
Corner taken right-footed by Rossi Jarvis from the left by-line to the near post, clearance made by Theo Streete.9:31
Josh Coulson gives away a free kick for an unfair challenge on Leigh Franks. Phil Barnes restarts play with the free kick.9:03
Free kick awarded for an unfair challenge on Michael Gash by Darran Kempson. Direct free kick taken by Joe Anderson.8:33
Theo Streete has an effort at goal from outside the penalty box which goes wide right of the target.7:29
Connor Franklin sends in a cross, Rory McAuley manages to make a clearance.5:06
Danny Meadows fouled by Charlie Wassmer, the ref awards a free kick. Free kick crossed right-footed by Josh Law from left wing, comfortable save by Craig Ross.2:34
Unfair challenge on Connor Franklin by Rossi Jarvis results in a free kick. Direct free kick taken by Leigh Franks.0:55
Nathan Arnold gives away a free kick for an unfair challenge on Luke Berry. Rory McAuley restarts play with the free kick.0:00
The match gets underway.
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