Amorim will lead Sporting CP tonight against City in the Champions League, with his move to United now a week away.
Bernardo said at his pre-match media conference: "Before he arrived Sporting didn't win the league for nearly 20 years but since he's been there with the president and the sporting director it looks like they all went in the same direction.
"When that happens and people are competent and have the same idea and go the same way, the chances of doing well are much higher.
"As a manager tactically, you can see that he's really good, the way he prepares his teams. Sporting are a big machine right now. I only have compliments because they've been flying in the Portuguese league. It's going to be very tough to beat them.
"In terms of him going to Manchester United, I don't wish him well but he deserves to be in one of the best clubs in the world right now because of the work that he has done for the last few years. He will be a rival but I am glad someone else from Portugal is in the best league in the world."