After the 1-0 loss to the Red Devils, Zola said he was surprised by how good Sir Alex Ferguson's side is defensively.
"I knew it would be difficult if they scored first," said Zola.
"You don't expect a team like that to be so strong defensively.
"You expect them to be so good going forward. But Alex has done a great job as always and they look very, very strong.
"For me it has been a positive match, I know that we lost but we were playing against the best team in Europe, if not the world, and we just lost by one goal.
"I am happy for my team. It has been another step forward for us even though we lost the game.
"I am sure it won't be easy for anybody to come here and beat us but they did it in a very professional way.
"They just punished the only mistake we made. Our goalkeeper only made one save. When you can win games like this you are very strong."