Paul Lambert spoke of his immense frustration at the 3-1 first-leg defeat at Bradford - but insisted the tie is far from over with a "very different" game on the horizon at Villa Park.
While Lambert took a sprinkling of positives from the chances created in the Capital One Cup semi-final clash, the boss bemoaned a haphazard defensive display, with set-pieces proving to be his team's undoing.
Despite the loss, Lambert said his team would "come out of the blocks" for the second leg at Villa Park, with a place at Wembley still up for grabs.
He said: "I'm really disappointed we lost the match. We're in a game now, that's for sure.
"You know what's coming with the set-pieces but we didn't defend them well at all. That's definitely what hurt us. That certainly wasn't good enough.
"You can't defend corners the way we did and expect to get away with it.
"We had a lot of the ball and their keeper made some good saves but if you don't defend set-pieces that's what can happen.
"We had a lot of chances and on another night they might have gone in but that's certainly not good enough.
"Set-pieces are a vital part of the game and you have to be able to defend them. We certainly didn't do that."
On the second leg in front of a bumper, fervent claret and blue support, he added: "It's half-time. We have another chance to retrieve this. We will see what happens in a fortnight's time.
"We're at home. We'll have the majority of the crowd with us. But we know what we have to do.
"We certainly have to play a lot better than that. It's a big game for us.
"It will be a different game at Villa Park, that's for sure. You have to regroup. That's what you have to do. We have to come out of the blocks. There's no grey area."
Make sure you're there to back the lads against Southampton.