Huddersfield coach Nathan Brown felt his Challenge Cup finalists took their eye off the ball as they succumbed to Bradford in the engage Super League on Sunday night.
The Giants were beaten 28-18 in their first outing since securing a place at Wembley as former Huddersfield centre Chris Nero scored two tries at the Galpharm Stadium.
The defeat ended a seven-match winning run in all competitions and bore the hallmarks of a classic cup hangover.
Brown said: "The things that helped the Giants to Wembley and to sit in third place, we just clearly didn't have in the first half.
"We tried our best to guard against that attitude side of the game but effort in the first half clearly wasn't acceptable.
"We asked for a response in the second half and we got a good one, but you cannot give away big starts like that.
"Bradford played some good footy, they came up with some nice plays and scored some nice tries.
"You need to give them credit for that but I think we saw, when we muscled up and decided to put in the required effort, things fell in our favour."
Huddersfield took an early lead through Brett Hodgson but Bradford responded to take a 24-6 lead in at half-time with Nero's double and further tries from Michael Platt and Paul Sykes.
It was play-off quality football from the Bulls but they still look unlikely to make the top eight.
"It is completely out of our hands, but we have just got to keep trying to win games," said coach Steve McNamara.
"But I'm really pleased for the group, I feel we are starting to get a little bit of the reward we've deserved throughout the season.
"It was a good performance from us, the first and second halves were different in terms of the quality shown, but we got the job done."
Bradford managed just four points in the second half as Paul Deacon took his goal tally to five.
Huddersfield fought back through Scott Moore and Danny Kirmond but the damage was already done. The game did become scrappy in the second half and one of a number of controversial incidents saw Moore sin-binned and placed on report for a late tackle on Deacon.
Brown said: "If he (Deacon) wanted to he could have stayed down, so you've got to give him credit for getting straight up.
"That probably shows what was in the incident - not a great deal."
Huddersfield will assess the fitness of Stephen Wild, who left the field with a knee injury, on Monday.