The Saints had a man sent off in the second minute of the game and went on to ship four goals before half time.
They conceded another five and received another red card in the second half.
"The squad feeling is that we've made this experience once and what happened afterwards was a reaction that everyone wanted to show," Hasenhuttl told reporters ahead of Saturday's trip to Newcastle.
"Games like this can happen from time to time. It's up to us to show what team we are.
"The good thing is, after every setback, you see new hope."