Daniel Farke says a below-par first half left Norwich City with too much to do as they fell to a 4-2 defeat at Aston Villa on Saturday.
Goals from Conor Hourihane and Andre Green put Villa in control, and although City responded after the break, they were always left chasing the game.
"It was a bid first half and Aston Villa deserved to be in the lead at half-time," Farke told Norwich City TV.
"We reacted well to that and scored again. There was momentum on our side then we stopped playing at a handball and they made it 4-2.
"When you concede such a goal after 82 minutes it's tough to come back again. We have to accept it and concentrate on the things we can influence.
"I'm more annoyed and concerned by the first half. We have to improve."
On the changes he made to his side from Wednesday's win over QPR, Farke explained: "It was our third game in six days.
"We had to do without Ivo Pinto because he felt pain in his back after training yesterday. Marley Watkins had some problems with his foot and this morning we thought we'd have to do without Nelson Oliveira.
"He had some problems with his groin and didn't feel good. After treatment it was much better but it was a risk to give him minutes on the pitch.
"Hopefully there will be no new problems. He's important for our game and is in good shape.
"I won't complain about these things. Although we did without those players we could have played a better first half; that's what we have to concentrate on."