"Why am I confident? Simple, because we have the best players in the world," he told The Sun.
"We have the confidence wherever we go. OK, we know Porto are a very good team, play good football and showed their own strengths at Old Trafford but it may be more difficult for them now.
"When you're at home you have to go forward more, and that could leave them under pressure. We are going there to win and we're confident we can do it.
"At the end of last season I thought the next one was going to be my year," he admitted.
"Maybe it's not gone how I would like, but I had injuries at the start and everything changed.
"You just have to be ready when you get the chance - I only hope next season will see me play more games.
"But if this season finishes at Rome and Wembley, plus another league title, it would be fantastic."