The Japan international signed a four-year deal at Old Trafford in June after joining from reigning German champions Borussia Dortmund.
Rooney, who scored 27 Premier League goals last season, has been impressed by the attacking midfielder in pre-season, and the England international is looking forward to playing alongside Kagawa.
“Shinji’s settled quite quickly,” said Rooney. “He’s a talented player, he likes to get on the ball and keep it simple.
“He’s very effective on the ball. It’s great to have that sort of player in the team.
“I’m looking forward to playing with him and I think he’ll create a lot of chances for myself and the other forwards. It’s exciting to have him in the team.”
United face Barcelona in a pre-season friendly on Wednesday, and Rooney is confident the match will provide a real indication of the squad’s fitness ahead of the new season.
“It’s great to play in big games and Barcelona is one of them,” added Rooney.
“It’s all part of our preparation and we need to make sure we do the right things. We want to enjoy the game and get our fitness ready for the first game of the season.
“The result, in some ways, isn’t the most important thing. What’s important is the fitness and the sharpness. I’m happy with how I’m doing. I’ve been training for almost two weeks and I’ve been working hard. Everything’s going well so far.”
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