Remi Garde blamed a "lack of efficiency" in front of goal for Aston Villa's defeat at fellow strugglers Sunderland on Saturday.
Villa were undone by a Jermain Defoe brace as the hosts ran out 3-1 winners at the Stadium of Light, leaving Garde's side 11 points adrift of safety.
Carles Gil had offered the visitors hope with an acrobatic volley to level the scores after Patrick van Aanholt's deflected opener but Defoe struck twice to plunge Villa closer to the Premier League trapdoor.
The Frenchman told Sky Sports News: "It's a big disappointment. We didn't play too badly, the teams were close in terms of level but we didn't score and then conceded too many, it's as simple as that.
"I'm not fed up, I'm just trying to do my job as best as possible, every day, every minute.
"I am disappointed because we didn't expect to lose here. We didn't play too badly but we need to be more efficient."
Garde vowed his Villa players, who were heckled by angry away fans as they boarded the team coach after the match, would continue to fight despite their situation at the foot of the table looking increasingly bleak.
"The confidence has not grown with this kind of result but we still have life in front of us but it's more and more difficult," he added. "But until there is no light in front of us we must still believe."
Former Lyon boss Garde also confirmed he had refused to shake hands with Sunderland counterpart Sam Allardyce at the final whistle.
He explained: "I would have preferred that Mr Allardyce had come to me before the game to say hello. I find it quite easy to come after the game."