Wolves manager Stale Solbakken expressed concern over his team's mental strength after losing to Nottingham Forest.
Adlene Guedioura's stunning winner handed Forest the spoils, leaving Wolves struggling in 17th spot and without a win in eight games.
With three points from eight games, Solbakken said: "After conceding the second goal we looked like a team that had not won for a while.
"You could see that in the way that we passed the ball. Safe balls went wrong and many players made the wrong decision. That is often down to a lack of self-belief and that has to go before we play Millwall on Tuesday.
"We have not lacked it before but you could see it after we went 2-1 down. We have to work on that because if you are afraid of something you will never turn the corner.
"We need to believe in what we are doing and I think it was a bit to wild west sometimes. I was not happy with the way we defended.
"It was too open and we allowed them to counter-attack. There are very small margins but if you have not won in eight games then it is also a bit in the head as well.
"When they scored the second goal we struggled to get the rhythm in the game and they made it difficult for us."