Paul Sturrock rated Southend's 2-0 defeat at relegation-threatened Bradford on Friday as their season's worst away performance.
James Hanson's 13th goal of the season and Craig Fagan's penalty, after Sean Clohessy was sent off for tripping Nahki Wells, put another dent in Southend's promotion hopes.
"We are an exciting team usually and I am bitterly disappointed," said Sturrock after the League Two reverse at Valley Parade.
"This and other results leave us long shots to go up automatically, but we will fight to the end and miracles do happen. Two more wins should get us into play-offs."
To compound Southend's misery, they finished with nine men after substitute Elliot Benyon was red-carded when he appeared to kick Bradford left-back Rob Kozluk.
Sturrock felt Clohessy's dismissal was "a bit harsh", but added: "I have no arguments with the second one and he will disciplined."