"Derby will be a bit disappointed, and maybe the scoreline flattered us a bit," said the former Scotland midfielder.
"They started brighter than us. But goals change matches, and we were pleased to accept the rub of the green.
"Our away form is as good as any. But we have disappointed at home, and this was a massive result for us.
"Now the next match here against Reading on Boxing Day can't come quickly enough for us."