Milan won 5-0 in Austria, with new arrival Yacine Adli also scoring.
Messias said: "We have shown that we are strong, who we are.
"The team is the same, only a few have arrived. Adli, Origi, there is the same mentality, sacrifice oneself for the team."
"Scoring is always nice, I try to do my best by scoring and moving in the defensive phase. I try to make a little sacrifice.
"Adli already has the Milan mentality He has character, he immediately joined the group.
"People are saying that we are fifth or sixth, we continue on our way and see where we will arrive. The group, the union, the sacrifice, are our secrets."