There have been a bitter rivalry between the Gunners and United in recent years, and the news will most likely shock Arsenal fans.
But Fabregas insists his love for United will not stop him from ending their hopes of winning the Champions League.
Fabregas told News of the World: “I have no problem saying United are one of the best clubs in the world – even though I want to beat them.
“They are the best side in the world at the moment – a top, top side and we respect them a lot.
“In fact, they are one of the best clubs in history. I respect Alex Ferguson for what he has achieved.
“There have been some great battles over the years and I am sure these two games will be just as interesting and dramatic.
“Rooney and Ronaldo are amazing. I really and admire them for what they do.
“They have been excellent players from an early age and it’s unbelievable how they have maintained their amazing standards.
“I am a big fan of both of them. You can expect just about anything from them and they always make a difference in games. Look at Ronaldo against Porto – what a goal! It was one of the best goals I’ve seen.”
Fab added: “The rivalry is normal because, over the years, both clubs have been battling each other to win the big trophies.
“United are probably our biggest rivals but they are a team who play good football.
“You always enjoy these games but we are determined to come out on top.
“There is always good football in games between the two of us. They like to create and we have a go, so it’s tremendous for the supporters.
“At least we know we can beat them as we proved at The Emirates. They had their best players in the game earlier in the season and we won. That gives us tremendous confidence.”
