Gary Rowett said Burton Albion looked like the team gunning for a play-off berth and not his Derby County side following their 3-1 defeat at the Pirelli Stadium on Saturday.
The former Burton player and manager returned to the Pirelli as Derby boss for the first time and was made to endure a difficult afternoon on the side-line.
Rowett's Rams dropped out of the play-off places for the first time since November after a chastening defeat that made the 43-year-old question the "desire" of his players.
And Rowett lamented the "three mistakes" his side made in the lead up to goals from Liam Boyce, Luke Murphy and Lucas Akins that made sure of the points for Albion.
"You know what the game's going to be like regardless of whether Burton, before the game, thought they weren't playing for much other than local pride - it was enough for them," Rowett said.
"They showed a brilliant appetite.
"I think it's one of those games where if I use the word 'embarrassing', it looks like I'm taking credit away from Burton, because at the end of the day they've outworked us and showed a lot more desire and fight to get the result.
"I can't criticise that in any way, but if I look at my own players, it was very similar to the Sunderland game.
"We've been outworked by our opponents, we've lost 50-50 challenges that our opponents have shown more desire to win.
"We've given away three goals where we've made mistakes for all three of the goals.
"I think for the first one we give the ball away on the righthand side and they end up capitalising on it.
"The second one we give the ball away on the lefthand side between two players, it's really sloppy.
"And the third one we give the ball away on the edge of the box.
"So they've still got to go away and show the quality to show the quality to score afterwards, and I give Burton credit for that, but we make three mistakes.
"That's seven goals we've conceded against Sunderland and Burton who were both bottom of the league respectively
"We went one goal conceded in open play from 15 league games this season, so you can see where our problems lie.
"We've just been giving goals away to the opposition and when you do that - statistically the side that scores first in the championship virtually always wins.
"And if you give that to the opposition and then get a goal back to make it 1-1, a very good goal with Nuge scoring his first for a while, to then concede straight before half-time in a similar fashion was of course very frustrating.
"It was a tough afternoon and again, I give Burton huge credit, but they look like the team looking desperate to get into the play-offs, not us."