So who is he? Adnan Januzaj was born in Brussels to Kosovan-Albanian parents in 1995 and joined Anderlecht as a 10-year-old. A precocious talent, he joined United in March 2011 for a fee reported to be £297,000.
What happened then? He was soon playing for Paul McGuinness's Under-18 side but a serious injury disrupted his first year. He returned stronger, however, and it was not long before he was playing regularly for the Under-21s.
What did Sir Alex Ferguson make of him? A big fan from the start. Earlier this year he told the Manchester United website: "Adnan is a beautifully balanced player. He's only 18 and has to grow into his frame but he has good balance, good acceleration and is a very good technical player."
What about the first team? Ferguson gave him a squad number (44) and put him on the bench for his final match in charge at the end of last season. David Moyes then gave him his debut in the Community Shield against Wigan.
Has he got a long-term contract? No, and his agent has said that several clubs are interested – such as Manchester City, Real Madrid and Chelsea. United will want to act quickly, though, to extend his current deal to avoid losing him like they lost Paul Pogba to Juventus.
Is he the first United player to score twice on his first start in the league? No. A certain Ruud van Nistelrooy did too.
And who will he play for internationally? Options galore: Belgium, Albania, Kosovo (who can play only friendlies at the moment) as well as Turkey and Serbia, according to some reports. And then England in 2018 …
And why would he choose England ahead of Belgium? Now that's a tricky one …