Wolves travel to Goodison Park tonight needing to bounce back from a 4-2 defeat to Bournemouth that was full of individual errors.
The head coach - insistent that his players will fight until the end - wants his senior stars to 'take big responsibility' during the difficult moments and to stop the erratic errors.
"The boys are aware of it, they are working hard on it, we could do with more voices maybe," O'Neil said when asked about needing a calming presence on the pitch.
"They are developing too. Look at Joao's transformation from young potential to senior member of the team that has a voice. Toti the same.
"Mario, Matheus, Dawson, Jose and Nelson needs to take big responsibility in those moments. The ones that have played in a lot of big games at a high level.