Ronaldo left United for Real Madrid in a world record £80million move this summer and Owen will take his number seven shirt at Old Trafford.
“Manchester United did well to give him the number seven,” the Portuguese star said.
“He is a great player, an English player. He has everything to win there. He is at a fantastic club.”
“I arrived at Manchester when I was 18 years old and I’d been there six years and I think it’s a lot of time,” he said.
“I won many things there, collective and individual trophies and awards, and I met very good people there, good friends – so it’s not easy you know.
“Life is a challenge and I’m a man of challenges. I think it’s a good move.”