An improved performance by the U’s yielded no reward, as Doncaster scored seven minutes from time at the Keepmoat Stadium.
It was a bitter pill to swallow, with the U’s controlling large parts of the game, especially in the first period.
That first half saw the U’s dominate and they certainly deserved to go in at half time at least level, and they thought they would have a lead with the ball in the net on forty four minutes.
Unfortunately, Josh Thompson’s header was ruled out for a foul, with Anthony Wordsworth seemingly the player penalised by the referee.
After the break, the U’s were still marginally on top but they were beaten by a David Cotterill winner on eighty three minutes.
He curled in a fantastic effort over and around Cousins, that gave his side the three points.
Dunne made three changes to the U’s starting line-up, bringing in Michael Rose and Josh Thompson in defence and Dominic Samuel in attack.
Clinton Morrison and Matt Heath dropped to the bench and Dan Potts returned to West Ham, hoping for involvement in the Hammers’ game against Manchester United.
Doncaster, looking to go top of League One, bought in new signing Emile Sinclair in attack as their only change to the starting eleven.
Both sides looked to get forward in the early stages but neither keeper was tested by half chances at either end in the first ten minutes.
Brian Wilson, with a left foot shot from distance, and Marcus Bean, with a header, had efforts off target, with the same being true at the other end as Jones headed over.
On eleven though, the U’s did make Woods work as Drey Wright received a pass from Anthony Wordsworth.
The U’s youngster, in fact the youngest player currently playing in League One, cut inside his defender and bought a near post save out of Woods.
Debutant Dominic Samuel rose highest from the resultant corner but could only guide his header over the crossbar.
The U’s had settled well and the next attack saw the ball fall to Wordsworth on the edge of the area, unfortunately the shot was miscued wide.
On eighteen minutes, Cousins had to be sharp to get to a low cross first, allowing Kem Izzet to complete the clearance after Doncaster attacked down the U’s left.
A minute, the home side went close with an effort from loanee Sinclair that whistled just wide of Cousins’ right hand post.
At the other end, Rose whipped in a corner but following Bean’s header into the danger area, Okuonghae couldn’t guide his headed effort on target.
More good work from Rose, this time in defence, eventually led to fellow full back Wilson playing in Bean, who had a shot blocked.
Kem Izzet suffered the same fate on thirty one minutes, and a minute later Samuel headed wide from a Wilson cross as the U’s continued to ask the most questions.
Samuel then had a shot saved by Woods but the flag was already up for an offside as the ball was threaded through to the youngster.
In a rare home attack, Syers shot wide under pressure from Wordsworth but it was the U’s who had the final effort of the first half.
Brian Wilson whipped in a free kick from wide and Josh Thompson rose above everybody to head home into the bottom corner.
Unfortunately, the referee had spotted a foul in the box and gave a free kick to Doncaster, seconds later blowing the whistle to end the first period.
The U’s had dominated proceedings and could think themselves unlucky not to be ahead, with nothing untoward being seen from the Press Box when Thompson put his header in.
Dean Saunders couldn’t have been happy with his side’s efforts in that first half and his half time team talk almost had a desired effect on fifty one minutes.
A free kick was launched towards the U’s box, Jones won a header and Cousins had to produce a great reflex save to deny Iain Hume.
Wright was causing a few problems for the home defence and around the hour mark, he had two efforts just off target.
In between those chances, Hume had another effort superbly blocked by Bean at the other as the home side tried to exert some pressure on their visitors.
Halfway through the half, Dunne made his first substitution, bringing on Jack Compton for Drey Wright.
On seventy five minutes, the U’s boss was forced to make his second change, with Izzet limping off with what looked like an ankle injury.
Andy Bond came into the U’s midfield to replace the U’s captain, with Bean dropping into the deepest position of the trio in the middle of the pitch.
With eighty three minutes gone, the home side went ahead thanks to a rare bit of brilliance.
Cotterill picked the ball up wide, went past Brian Wilson and then curled a fantastic effort over and past Cousins.
It was a massive blow to the U’s, who had been the best team for much of the afternoon.
Porter was bought on with three minutes remaining and Thompson went up front as the U’s looked for an even later equaliser.
Unfortunately, it didn’t come and the U’s run of defeats moved onto eight, despite the much improved performance by Dunne’s men.