The Belgian's representative says the 19-year-old is the highest paid young player in the world and was the subject of an "insane" offer from Paris Saint-Germain last October
The Belgian has made 33 appearances this season after being given his first-team debut by former manager David Moyes and signed a five-year contract with United back in October.
Prior to signing the deal, Januzaj's agent claims the 19-year-old was targeted by several of Europe's top clubs and revealed that Paris Saint-Germain launched an "insane" last-ditch offer.
"I can only say that he is the highest paid young player in the world," Dirk De Vriese told Sport/Voetbalmagazine.
"At 18, he has a larger contract than Cristiano Ronaldo or Lionel Messi at that age. That really says a lot and I'm very proud of that.
"All the big clubs have pulled at his sleeve. Especially Paris Saint-Germain, who wanted to go very far for him.
"Five minutes before we signed the contract extension [with United], an adviser to the president of Qatar offered us an insane deal.
"Because Adnan could have left as a free agent, the Qatari investors were able to do the impossible. As well as with his salary, as with the signing on fee."