The Belgian winger is hoping to revive his career at the Stadium of Light after discovering he was not in Jose Mourinho’s short-term plans for the 2016/17 campaign.
The 21-year-old was allowed to leave Manchester United for Wearside on a season-long loan deal during the summer, although his Old Trafford departure caused many to question his apparent lack of progress since bursting onto the Premier League scene as a teenager.
However, Januzaj insists his career has not stalled, and he is ready to use consistent first-team football as a way to prove his doubters wrong.
Speaking to the Sunderland Echo, Januzaj said: “It is not to re-establish myself, it is just to prove to some of the people that they were wrong. I will work hard to show they were wrong over the past few years.
“Part of my mentality is to never give up. Even if something goes a bit wrong, you always have to keep working – that is what I have been doing. Now I have the chance to prove myself again.”
Januzaj, who spent the first half of last season on loan at Borussia Dortmund, was handed his senior debut for United by then manager David Moyes at the start of the 2013-14 season, and the midfielder admitted he jumped at the chance of a reunion on Wearside.
He said: “I spoke with the manager and he asked me if I wanted to come here. I said that I wanted to play football. He gave me the opportunity to do that and I am really thankful for that.
“He is building a very good team here. It is still early for him to show people what he can do, he needs time to adapt to the club, of course. But I think he is doing very, very well and all of the players that have been signed are all very good players.”