Michael Gash's injury-time penalty secured Cambridge a point at Alfreton Town in the Blue Square Bet Premier.
Josh Law's 25-yard free-kick - his first goal of the season - put the hosts ahead in the first half.
Tom Elliott went close for Cambridge, while Tom Shaw saw his goal-bound shot deflected wide by Darran Kempson.
Theo Streete was shown a second yellow card and was sent off for a foul on Harrison Dunk and Gash kept his cool from the spot in stoppage time.
VIEW FROM THE DRESSING ROOM
Alfreton Town manager Nicky Law told BBC Radio Derby:
"I am very disappointed. They have made all their subs, they have chucked all their options at it and we have got the game.
"We make a poor decision when Nathan Arnold is through. He has only got to roll it in to Dan Bradley into an empty net and it is 2-0 and game over.
"We haven't got the killer instinct, that's all we needed to see it through. We needed someone to take charge of the situation.
"We didn't go and play on the front foot in the second half. The ball was coming back far, far too easy and we were back to where we were a bit ago.
"In the second half we are 1-0 up and suffer a bit of panic where we make the wrong decisions. At times like that, you need a little bit of composure and you just do your job. Too many of them have not done that tonight and it has cost us in the end."
Cambridge United head coach Richard Money told BBC Radio Cambridgeshire:
"I think a point is the least we deserve if I'm honest. I thought we deserved to win by some margin.
"We were wasteful in front of goal, but it was a good team performance and I think everyone here tonight can see there is a good team emerging.
"We looked solid, we looked stable, we didn't look in too much trouble and we are playing some good football at times."
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Live Text Commentary
Full Time The game is over, as the referee blows his whistle.90:00 +3:59
Shot by Harrison Dunk. Save by Jon Stewart. Corner taken by Robbie Willmott.90:00 +3:03 Goal scored
Goal! - Michael Gash - Alfreton 1 - 1 Cambridge Penalty taken right-footed by Michael Gash and scored. Alfreton Town 1-1 Cambridge Utd.90:00 +2:11 Dismissal
Dismissal Theo Streete is shown a red card.90:00 +1:51
Theo Streete gives away a Penalty for an unfair challenge on Harrison Dunk.90:00 +1:00
Shot from just outside the box by Ricky Wellard goes over the target.90:00 +0:05
Unfair challenge on Rory McAuley by Paul Clayton results in a free kick. Josh Coulson restarts play with the free kick.87:59
Free kick awarded for an unfair challenge on Michael Gash by Leigh Franks. James Jennings restarts play with the free kick.87:17
Foul by Dan Bradley on Rory McAuley, free kick awarded. Free kick taken by Craig Ross.86:32
Shot by Michael Gash. Jon Stewart makes a comfortable save.85:18
Shot from just outside the area by Tom Shaw goes over the bar.84:44
The ball is swung over by Kevin Roberts.82:53
Shot comes in from James Jennings from the free kick.82:53 Booking
Booking Ross Killock goes into the referee's book.82:45
Unfair challenge on Tom Shaw by Ross Killock results in a free kick.81:31
Free kick taken by James Jennings.81:31 Booking
Booking Booking for Theo Streete.81:26
Theo Streete gives away a free kick for an unfair challenge on Ricky Wellard.80:50
Shot by Robbie Willmott. Save made by Jon Stewart.79:23
The ball is swung over by Dan Bradley, save made by Craig Ross.
Free kick awarded for a foul by James Jennings on Nathan Arnold. Jon Stewart takes the direct free kick.77:58
Corner taken right-footed by Robbie Willmott from the left by-line, Paul Clayton makes a clearance.76:28 Substitution
Substitution Darran Kempson goes off and Leigh Franks comes on.74:29
Robbie Willmott is caught offside. Indirect free kick taken by Jon Stewart.74:11
The ball is crossed by Harrison Dunk.72:17
Josh Law gives away a free kick for an unfair challenge on Harrison Dunk. James Jennings restarts play with the free kick.70:27
Harrison Dunk crosses the ball, Josh Law manages to make a clearance. James Jennings crosses the ball, clearance by Josh Law. Inswinging corner taken left-footed by Ricky Wellard from the right by-line.68:09
The offside flag is raised against Paul Clayton. Craig Ross restarts play with the free kick.67:15 Substitution
Substitution Tom Elliott leaves the field to be replaced by Jonathon Thorpe.65:04
Foul by Paul Clayton on Rory McAuley, free kick awarded. Craig Ross takes the direct free kick.64:44
Josh Coulson gives away a free kick for an unfair challenge on Nathan Arnold. Anton Brown restarts play with the free kick.64:10
Dan Bradley is ruled offside. Craig Ross restarts play with the free kick.63:33 Substitution
Substitution Ricky Wellard replaces Rossi Jarvis.60:44
The referee blows for offside. Craig Ross restarts play with the free kick.59:42 Substitution
Substitution Robbie Willmott comes on in place of Andy Pugh.57:57
Rossi Jarvis challenges Theo Streete unfairly and gives away a free kick. Direct free kick taken by Darran Kempson.57:01
Darran Kempson gives away a free kick for an unfair challenge on Michael Gash. Free kick taken by Rossi Jarvis.55:10
Effort on goal by Nathan Arnold from just inside the area clears the bar.54:47
Tom Elliott delivers the ball.53:50
Matty Harriott fouled by Tom Shaw, the ref awards a free kick. Jon Stewart restarts play with the free kick.53:15
Save by Jon Stewart.53:15 Booking
Booking Jon Stewart receives a yellow card for time wasting.52:11
Shot from 12 yards from Rossi Jarvis. Jon Stewart makes a save. Inswinging corner taken by Rossi Jarvis, Ross Killock manages to make a clearance. Outswinging corner taken by Rossi Jarvis from the right by-line,47:51
Shot by Andy Pugh from outside the box goes high over the crossbar.46:03
Free kick awarded for an unfair challenge on Tom Elliott by Matty Harriott. Rossi Jarvis crosses the ball from the free kick right-footed from right channel.45:01
The referee gets the second half underway.45:00 +2:08 Half time
Half Time The half-time whistle blows.45:00 +0:57
Centre by Josh Law, Header from deep inside the area by Anton Brown goes over the bar.45:00 +0:57 Booking
Booking Kevin Roberts shown a yellow card.45:00 +0:48
Foul by Kevin Roberts on Paul Clayton, free kick awarded.43:50
The ball is crossed by Andy Pugh, Matty Harriott gets a block in.42:35
Harrison Dunk takes a shot. Jon Stewart makes a save.41:43
Dan Bradley produces a right-footed shot from just outside the box that goes wide left of the goal.40:50
Free kick awarded for an unfair challenge on Tom Elliott by Darran Kempson. James Jennings delivers the ball from the free kick left-footed from left channel, James Jennings makes a clearance.38:39
Paul Clayton is caught offside. Craig Ross takes the indirect free kick.36:18
Tom Shaw has a drilled shot. Darran Kempson gets a block in. Rossi Jarvis takes the inswinging corner, Paul Clayton makes a clearance. A cross is delivered by Rossi Jarvis, clearance by Anton Brown.34:58
Tom Shaw sends in a cross, Jon Stewart makes a save.34:38
The ball is crossed by James Jennings, Connor Franklin makes a clearance.32:45
Josh Law delivers the ball.32:07
Corner taken by Josh Law, Kevin Roberts makes a clearance.31:38
Theo Streete sends in a cross, save made by Craig Ross.31:00
Paul Clayton fouled by Kevin Roberts, the ref awards a free kick. Ross Killock takes the free kick.29:48
Harrison Dunk gives away a free kick for an unfair challenge on Josh Law. Free kick taken by Jon Stewart.28:46
Foul by Dan Bradley on Craig Ross, free kick awarded. Free kick taken by Craig Ross.28:01
Rossi Jarvis challenges Connor Franklin unfairly and gives away a free kick. Free kick taken by Jon Stewart.27:07
Tom Elliott takes a shot. Save by Craig Ross. Outswinging corner taken right-footed by Rossi Jarvis from the right by-line, Jon Stewart makes a save. The ball is sent over by Rossi Jarvis, blocked by Paul Clayton.26:07 Goal scored
Goal! - Josh Law - Alfreton 1 - 0 Cambridge Josh Law hits the back of the net with a goal direct from the free kick from outside the box to the bottom left corner of the goal. Alfreton Town 1-0 Cambridge Utd.25:25
Rory McAuley challenges Paul Clayton unfairly and gives away a free kick.23:21
Tom Elliott produces a right-footed shot from deep inside the penalty area which goes wide of the left-hand post.22:07
Free kick awarded for a foul by Michael Gash on Theo Streete. Free kick taken by Jon Stewart.21:37
Anton Brown has a mishit shot and went wide right of the goal.20:41
Tom Elliott produces a right-footed shot from just outside the box that goes wide right of the target.18:24
Corner taken right-footed by Josh Law, save made by Craig Ross. Josh Law takes the inswinging corner, clearance by Rory McAuley. Inswinging corner taken from the left by-line by Josh Law.16:59
The official flags James Jennings offside. Jon Stewart restarts play with the free kick.16:25
Michael Gash is ruled offside. Ross Killock restarts play with the free kick.16:02
The assistant referee flags for offside against Paul Clayton. Craig Ross takes the indirect free kick.11:51
The ball is sent over by Tom Shaw.10:20
Josh Law produces a right-footed shot from just outside the penalty box that misses to the left of the target.9:12
Shot from inside the area by Tom Elliott clears the bar.7:31
Andy Pugh concedes a free kick for a foul on Connor Franklin. Josh Law crosses the ball from the free kick right-footed from left wing, clearance made by Rory McAuley.5:18
Inswinging corner taken by Josh Law from the left by-line, Headed effort from deep inside the area by Paul Clayton misses to the right of the goal.2:05
Foul by Rossi Jarvis on Paul Clayton, free kick awarded. Matty Harriott takes the free kick. Nathan Arnold is caught offside. Craig Ross takes the indirect free kick.0:20
Michael Gash challenges Connor Franklin unfairly and gives away a free kick. Free kick taken by Ross Killock.0:00
The referee gets the match started.
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