Cambridge United manager Colin Calderwood was left 'horrified' by the officiating for Northampton's second goal during their 2-0 defeat at the PTS Academy Stadium on Saturday.
Calderwood had no issue with Harry Smith's well-taken opener - despite suggestions of offside - but it was the second goal, scored in first-half stoppage-time, that left him frustrated.
Cambridge had already appealed for a foul in the build-up when Smith collected Shaun McWilliams' pass, seemingly in an offside position, and saw his cross diverted into the net by United captain George Taft.
"I have no complaints about the first goal but we've got huge complaints with the second goal," said Calderwood.
"We can be annoyed about ourselves for the first goal but we're horrified by the officials for the second one. It's definitely offside and it was a foul beforehand."
Calderwood was otherwise relatively satisfied with his side's performance despite suffering their sixth league defeat of the season.
"I thought the start gave us a foundation in the game and we were pretty good in the first period," he said.
"We had some invention from set-pieces and we looked as if we might have a way of conjuring a chance in the awkward conditions.
"I can't really complain apart from the moment where we lost the first possession from a throw-in and made a mistake for the first goal.
"We haven't backed off and we haven't defended a through ball and had we done that it would have made it a lot harder to score.
"We looked like we could have scored in the second-half and we had a couple of half chances but I'd have liked us to be a bit more dangerous - until you get one goal back you're never in the game."