Cambridge United boss Richard Money believes Ryan Donaldson's goal in the 1-0 loss to Rotherham on Tuesday in the Capital One Cup should have stood.
Donaldson slotted home in the 90th minute, but was deemed offside.
"I thought it was a goal. I don't think it was offside and it's gone in," Money told BBC Radio Cambridgeshire.
"But as ever with linesmen, they look too late. By the time he receives it he might be in an offside position but the pass is perfect."
Money continued: "I'm not sure whether we wanted another 30 minutes if I'm honest, having travelled here and then going up to Carlisle on Friday."
Cambridge's narrow defeat by the Championship side came after a 3-0 victory over Newport in League Two.
And Money says that his team, who have added 11 summer signings to their squad, are showing promise.
"I thought it was alright and there were some signs of real potential," he said. "The way we're trying to play is putting a demand on them to pass it and keep it.
"Fitness levels are probably just not quite there in terms of decision making, but there are signs of what we could and might become."