Stephen Rochford pinpointed Adam Gallagher's missed goal chance as the moment the tide turned for his Mayo team after their Allianz Football League Division 1 defeat to Dublin.
Gallagher curled a glorious chance wide when he was played clean through early in the second half.
A goal at that point would have reduced the deficit to two points but instead the Dubs remained five clear and they always had their opponents at arm's length as they closed off a 2-10 to 0-12 win.
"It's disappointing," Rochford said afterwards.
"We had prepared this week (to win) that game. Just after half-time we created a really good goal chance and didn't take it.
"Maybe we would have asked Dublin more questions if we had.
"We coped quite well. There was plenty of learning there for new guys. There are some positives and still a number of things we'll be working on, but the league has a number of objectives and one of them tonight was to win two points and we didn't do that."
One big plus for the hosts was the return to action of Lee Keegan.
Rochford expects the 2016 Footballer of the Year to improve as the campaign progresses, with more stern test on the horizon.
"I thought he adapted quite well to his first game in four and a half months," said the manager.
"That graph will obviously to push upwards. There's another big game next week against Kildare for him and for the rest of us."