Jim Bentley labelled Morecambe's capitulation as "unacceptable" after they blew a two-goal lead to lose 3-2 at home to Plymouth.
The hosts led two-nil on Saturday with just 20 minutes remaining thanks to goals from Jack Redshaw and Richard Brodie, from the penalty spot, and looked set for their first home win of the season.
But a Ross Jenkins wonder strike and two penalties from Warren Feeney handed Argyle a memorable victory - their first on their travels this season.
Bentley said: "You should never lose a game at home when you are two-nil up with 20 minutes to go and it's totally unacceptable.
"We have got enough experience in the squad to see games out like that and I still can't believe we haven't got anything from the game.
"We got the goals and played some good stuff but didn't really stamp our authority on the game like I was hoping we would, but we should have seen it out. As soon as they got the goal we just crumbled and that is not good enough. We have to learn to see games out, especially at home."