David Moyes says Manchester United are close to agreeing a long-term deal for Adnan Januzaj, and hailed the teenager as an "exceptional talent" potentially in the same class as Wayne Rooney.

To say the football world was excited by Januzaj's full United debut at Sunderland would be an understatement. The 18-year-old Belgian rescued his teetering team with two goals, and Old Trafford is already impatient to see more when fourth-placed Southampton visit on Saturday afternoon.

Moyes attempted to manage expectations by denying Januzaj is already a fixture in the team after one game. "Hardly anyone plays week in week out for Manchester United and you wouldn't expect to find an 18-year-old doing that," said the United manager but otherwise he could scarcely conceal his own admiration for the teenager.

"He's a really good player who is going to be able to play in several positions, only time will tell what his best one is going to be. He could arguably play centre-forward with his back to goal, he's good coming off the left or the right, and maybe with a bit more experience a number 10. He's a maker of goals but as you saw at Sunderland he's got goals in him as well. He's an exceptional all-round talent."

Similar praise was showered on Federico Macheda four years ago, an Italian import who never quite reproduced his initial brilliance and ended up being loaned out to Queens Park Rangers and Doncaster Rovers. Moyes is convinced Januzaj's quality will prove more lasting. "I can only judge him against some of the other top young players I have seen in my career," he said. "That would include Charlie Nicholas at Celtic, Paul McStay, Wayne Rooney at Everton, Ross Barkley. I would certainly put Adnan in that category. He's not out of place among those names. And you've got to remember he's 18 years old. He's still a young boy. Some players, good players as well, have played for their clubs aged 18, but I think to play for Manchester United when you are that age is a big thing."

Januzaj has yet to decide which country he wants to represent in internationals and has yet to commit himself to United beyond his present contract which expires in a year, though he says he is keen to stay. "I am happy at Manchester United and want to commit myself 100% in every game," he told Kosovo's KTV. "I want to help Manchester United win the Premier League and become the best player in the world."

The player does not lack ambition, though Moyes claims he is a level-headed, humble boy. "He's got no real ego to him, he doesn't mind playing in the youth team or the reserves, and he's been really well looked after by his dad and his family. That's kept him the right way and I think he'll be able to handle anything that comes along. I want to get the contract done and so do the club but I am confident. When you are 18 years old and you are playing for Manchester United, you have broken into the first team, I don't know where else in the world you would really want to play. He's in and around the first team now so hopefully that will all be sorted."

Moyes is aware of United's traditions when it comes to giving young players a chance and equally aware that after three defeats in seven games he has to put out a side capable of winning matches. It is a measure of his confidence in Januzaj and his own judgment that he successfully gambled at Sunderland. "I knew when I first took this job that part of the manager's responsibility here is to introduce young players," he said. "Sir Matt Busby's comments on the subject are on the wall in the dressing room area – if you are good enough you are old enough. That's been the philosophy of this club, the last manager put young players in when he had them and I will try to do the same because I think it's what they do well here. At the same time I need to get results like any other manager. If I don't people will have plenty to say, I'm not daft enough to think I'm any different. But I also know there's a long-term plan in place here and I am part of it, the board have reassured me about that. We have to keep looking forward. I might have to take a few punches on the nose to get to where I want to be but hopefully in the end we'll all be better for it."

Marouane Fellaini is to continue playing even though he needs an operation on his wrist. "We can put it off for a while, he can play with strapping," Moyes said. "The problem is that once he has the operation he could be out for four to six weeks. We don't really want to lose him for that length of time mid-season, so unless he picks up another injury or a suspension, we are looking at next summer, possibly after the World Cup."