This was no smash-and-grab away victory.

Colchester United are serious promotion contenders this season, and they proved it by inflicting a first home league defeat of the season over lofty rivals MK Dons on Saturday.

The U’s were good value for their slender 1-0 victory, secured via skipper Luke Prosser’s instinctive finish from Brennan Dickenson’s 12th minute corner.

The Dons had won eight of their previous 11 home league fixtures, with the other three drawn, but they rarely looked like preserving their unbeaten home tag against the masterful U’s.

Paul Tisdale’s men did exert some pressure in the second half, as was to be expected, but keeper Rene Gilmartin only had one real save to make, when finger-tipping Ousseynou Cisse’s rising shot over the bar, on 57 minutes.

In fact, the visitors could have put the game to bed themselves when Luke Norris skied a shot over the bar, with just keeper Lee Nicholls to beat from Ryan Jackson’s fine cross with 15 minutes remaining.

But Norris’ miss was not costly.

The U’s became the first away team to take all three points from Stadium MK, to cement their place in the top three. They will enjoy their Christmas, nestling in third spot, the last of the three automatic promotion places, and can look forward to the second half of the season with genuine optimism.

Inspired changes

Boss John McGreal made four changes to the side that were hammered 4-0 at Carlisle United the previous weekend, and only one of these was really enforced.

And as it happened, all four were inspired decisions, with the new quartet playing big roles in the U’s fourth away win of the campaign.

Keeper Renen Gilmartin, centre-half Tom Eastman and striker Luke Norris were all back in the starting line-up after recent injuries, while Brennan Dickenson was handed a rare start as McGreal opted for a three-man central defence.

Dillon Barnes had conceded four goals at Brunton Park, so it was a good time for the experienced Gilmartin to return to the side. The U’s goalkeeping coach has now kept four clean-sheets in his six league outings for the Essex club.

The 31-year-old inspires confidence in his defenders while Barnes, who is a very promising keeper, will have benefited from his two spells in the team.

Eastman’s return, after a six-week absence with a head injury, allowed McGreal to operate with three centre-halves, while Norris, although still not fully match-fit after his ankle injury, was not surprisingly preferred to Mikael Mandron up top.

The other change was enforced. Kane Vincent-Young failed a fitness test on a foot injury, and so in came Dickenson at left wing-back – Dickenson not only chalked up an assist for the winning goal, but was excellent all afternoon bombing up and down the flank.

Praise from opposing boss

Paul Tisdale, who left Exeter City after 14 years on the Grecians hot seat last summer, to take on a new job at MK Dons, was full of praise for the U’s on Saturday.

Tisdale has done well to consolidate the Dons as a top-three side, following relegation from League One last term, but he had no complaints with only his side’s third defeat from 22 league games,

“I’m disappointed with the way we played, but not that unhappy, because sometimes you have to give the opposition some credit,” said Tisdale.

“I thought Colchester did a good job on us. They managed to stop us playing.”

Clean-sheet heaven

Any promotion-seeking team needs a sound defence, a good platform to build on, and the U’s have that in abundance.

Saturday was their 10th clean-sheet from 23 league games, an impressive ratio.

The Dons had a lot of possession, and made attacking changes at half-time to try and turn the tide, but they found stubborn resistance in the shape of the U’s three-man rearguard.

Tough challenge ahead

Although the U’s will be in the top three on Christmas Day, they will probably have to up their game still further if they are to clinch automatic promotion in just over four months time.

Wycombe filled the last automatic slot last season, with 84 points from 46 games. So far, the U’s have acumulated 41 from 23 games. Matching that 41-point haul might just be enough (fourth-placed Exeter had 80 points last season), but it would be tight.