David Moyes says Sunderland will have secured a "top player" if they can get Adnan Januzaj back to the form when he first broke through.
The 21-year-old Belgium international is Moyes’ fourth signing as Sunderland boss.
The winger burst onto the scene two years ago, on the back of an outstanding performance against Sunderland, but his career has stalled.
"I want to give him the opportunity to show the Sunderland fans what he can do," said Moyes.
"He has got a level of quality which I want to add to the club and bring here and up the standards as we go and up the competition for places, more importantly.
"I want people who can win games by making or scoring goals – Adnan certainly has that.
"First of all, he has to come in and show me he is going to be a team player and if he does that and we can get somewhere close to the Adnan of two years ago, then we will have a top player here."
Born in Brussels, Januzaj began his youth career with Anderlecht before moving to United, where he has since gone on to make 50 appearances for the first team, garnering both Premier League and UEFA Champions League experience.
The winger spent part of last season on loan with German giants Borussia Dortmund, gaining further experience in European competition.
Januzaj is no stranger to the Stadium of Light, having scored a brace to give his former club a 2-1 win over the Black Cats back in 2013 on one of his first senior appearances.
Sunderland’s latest addition is available to make his debut against Manchester City on the opening day of the Premier League season tomorrow.