Saidy Janko
Janko has 'fantastic potential', according to Butt. (Twitter)

Manchester United's UEFA Youth League coach Nicky Butt has talked up the "massive potential" of the club's forgotten summer signing Saidy Janko.

The 17-year-old right back joined the club for a reported fee of £700k on transfer deadline day, a deal that drifted under the radar as United finalised a £27.5m for Marouane Fellaini.

The former FC Zurich starlet is yet to join up with his new club but having impressed against United's youth ranks during a summer tournament his coaches are already greatly impressed with the youngster's burgeoning ability.

"He's not available at the minute because we're waiting for international clearance. It could take time - weeks or months - we're not sure yet," the former United midfielder Butt told the club's official website.

"The important thing with Saidy was getting him signed up and having him training to get his fitness up and his potential out there because he has got massive potential."

The Switzerland under-19 international played for FC Zurich against United's young hopefuls this summer in the Blue Stars FIFA Youth Cup and his physical and technical attributes quickly impressed Butt and the club's Under-21 manager Warren Joyce as he helped his side secure a 0-0 draw en route to winning the competition.

"He played against us in the Blue Stars tournament and stood out straight away," Butt continued.

"Warren and I watched him a couple of times over there and when you see a player like him with his physical ability at a young age and ability with a football, it was a no brainer really.

"We were just lucky with the timing as we were there and he was playing against us and was available to get. Although it was a bit of hard work to do it, we've got him and it's just a no brainer because he has fantastic potential."

Janko is likely to join United's other low key summer signing Guillermo Varela in the club's youth ranks when the move is finally sanctioned.

The 20-year-old Uruguayan has started all three of United's Under-21 Premier League games this season at right back following his move from Penarol earlier in the summer.