Steve Cooper had no excuses as his Swansea blew the chance to go second in the Sky Bet Championship after a 4-1 defeat to Huddersfield.
Cooper admitted his side were "second best" as they slipped to a shock setback.
The match was 1-1 at the break but the hosts scored three second-half goals inside seven minutes to turn the game on its head.
Swansea could have moved into the automatic promotion places with a win but instead they remain fourth.
"We've only got ourselves to blame for today," admitted a dejected Cooper.
"If you don't do the basics, at both ends of the pitch, then it can cost you.
"The goals from Huddersfield were obviously good finishes, but the areas that they got into were ones we worked on a lot to try and prevent them getting into.
"The game was quickly out of sight in 10 or so minutes after the break.
"We were second best today and in this league, players can hurt you and that's happened.
"We didn't take enough care of the ball or play with even purpose.
"Defensively, we were just too passive. We weren't good enough at being ourselves today.
"It might be fatigue but I'm not going to use that as an excuse."
But the Terriers came out of the blocks quickly after the restart and scored three goals in quick succession.
First, he applied a fine finish from inside the box. Then, he unleashed a sumptuous shot from outside the area that flew into the top-corner.
Swansea's day went from bad to worse when Jordan Morris left the field on a stretcher before the hour mark. The visitors had already made their full allocation of five changes and had to play the final half-hour with just 10 men.
On the nasty-looking injury, Cooper added: "It doesn't look good. I don't know the exact damage or the extent of it.
"He's in a knee brace and is on crutches and is in a lot of pain. We've got our fingers crossed."
As for Town, they now have a seven-point buffer between themselves and the relegation places.
Terriers' boss Carlos Corberan said: "I think it was really important for us to win today and also the way that we did it.
"For me, it was important to play offensively. We wanted to have Campbell close to the last line so he could affect more situations.
"Swansea are a team who play well and have a good coach and play positively.
"We played with a lot of determination and courage and lots of quality, especially in the second half.
"When you have a negative experience, such as conceding just before half-time, the key thing is the confidence to bounce back.
"I cannot find one player today who didn't complete the game in the way we wanted.
"Duane is showing his adaptation. He was great and this was important for us.
"Sometimes the player needs time to be ready but I was happy with Duane.
"But all the players are going to be key for us, that's because we have a squad mixed with young or experienced players.
"We need everyone to work hard between now and the end of the season."