The striker played twice for England at Euro 2012 and returned to the United fold in Sunday's goalless draw against Valerenga following a short break.
With a tough test against Barcelona on the horizon, he is looking to use the match as another step towards regaining full fitness in time for the opening game of the season at former club Everton.
"It's great to play in big games and Barcelona is one of them," said 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.
"I feel good. I played two games in the summer and I played against Valerenga. Everybody needs games to get up to match fitness - not just me. I'm training well, though, and I'm looking forward to the next few games. Hopefully, by the start of the season, I'll be ready to play."
Rooney is looking forward to spending more time on the pitch with summer recruit Shinji Kagawa after playing for 15 minutes with the Japan international in Oslo.
"Shinji's settled quite quickly," he revealed. "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