Ravel Morrison could be forgiven for looking at Adnan Januzaj and thinking it should have been him. Manchester United might feel the same way about a player who was once described as the best talent to emerge at Carrington since Paul Scholes. Praise does not come much higher than that at United, where they know a thing or two about gifted youngsters.

No one has ever doubted that Morrison knows what to do with a football but what has been questioned is whether he possesses the necessary attitude. Talent on its own is not enough, as Jack Wilshere has been reminded in the last few days. Making sacrifices comes with the territory and it has not always been clear whether Morrison is capable of that in his short career, which is why Januzaj is the new teenage darling of the United support after his brilliant double on his full debut against Sunderland on Saturday.

A day later, though, it was Morrison's turn. With West Ham 2-0 up against Tottenham Hotspur at White Hart Lane, he collected the ball just inside his own half, accelerated away from Jan Vertonghen, beat Michael Dawson with a swerve and a drop of the shoulder and then delicately dinked the ball over Hugo Lloris, putting just enough pace and spin on the chip so Kyle Naughton could not reach it before it crossed the line. Now the world knows why there was such a buzz around the 20-year-old at United, why they were so excited about that intoxicating blend of deceptive pace, skill, balance, imagination and absolute belief in his ability. "It's the genius of Ravel Morrison," Sam Allardyce, his manager at West Ham, said.

It is a genius that has taken a while to flourish. United knew they had a potential star and he was the key player in the side that won the FA Youth Cup in 2011, catching the eye during the 3-2 win over Liverpool at Anfield. His second goal on that afternoon, a left-foot volley from the edge of the area, was rather like Januzaj's on Saturday. Yet United grew to despair at the regularity with which Morrison would fail to turn up for training. He was given a referral order for witness intimidation and then found himself back in court for smashing his girlfriend's phone after an argument with her.

"The referral order was imposed after he tried to intimidate the 15-year-old victim of a street robbery out of giving evidence. Morrison never seemed to understand the seriousness of sending threatening messages, then being part of the mob that chased the robbery victim and threw a brick through his window. The boy did. He was so traumatised his family put their house up for sale." Daniel Taylor wrote in the Observer in January 2012

By January 2012 Morrison's relationship with United had turned ugly. Sir Alex Ferguson was one of the last to give up on him, realising he needed to get away from Manchester, where there were too many people leading him astray. Top clubs had a look but none bit. Instead Morrison was forced to drop down a division, joining West Ham for £650,000.

It was a relatively low-risk gamble by Allardyce: if Morrison failed, well, even Ferguson, the master motivator, could not get him to knuckle down but if he stayed out of trouble then West Ham would have a very special footballer on their hands.

Those who know him talk of Morrison's naivety rather than his malice. Initially he struggled at West Ham. He did not walk into a side that won promotion, instead making headlines when he was fined by the FA for a homophobic tweet, and before the start of last season he was sent on loan to Birmingham City.

"As a young kid coming from Manchester thinking that he can walk straight into the team, I think that was a big shock to him that he didn't," Neil McDonald, Allardyce's assistant, said in August. "We have got some good players at this football club and he had to earn that respect. He didn't do that early on and we sent him out to Birmingham." "He took quite a big wage reduction from West Ham to come and play at Birmingham, which tells you a little bit about the lad," says Derek Fazackerley, a coach at Birmingham.

It was time for a player who had been forced to leave West Ham's pre-season tour of Germany to have seven teeth extracted after he had complained of toothache to grow up. But Birmingham's manager, Lee Clark, found him frustrating at first, although the issues were trivial.

"We were playing Middlesbrough one Friday night," Fazackerley says. "On the Thursday afternoon at about 3.30pm, I went down to get changed and I could hear this noise in the players' changing room next door to the training ground. When I walked through the door it's Rav and four or five of his mates and he'd been playing football on the top field of the training ground at half past three on a Thursday afternoon before we were playing on Friday. It was little things like that. The lad just wanted to play football and if he could play football 24/7, you wouldn't have any problems whatsoever with him.

"He'd turn up for a game and he'd have his suit in a carrier bag and he'd be wearing a tracksuit when everybody else was in a suit. At times he got caught out when maybe he'd travel back to Manchester on an afternoon and then was trying to get back to Birmingham the following morning and the train might have been late or he might have got held up on the motorway. Most of the stuff that he was in trouble for was trivial but obviously it becomes disruptive to the group when it happens more than once."

Gradually Birmingham were able to appreciate their rough diamond. Rio Ferdinand, who watched Morrison in training at United, said that Sunday's goal would not even make it into his top three. "There were several times in training he'd score a goal you couldn't believe," Fazackerley said. "He could chip goalkeepers from 25 yards which obviously didn't go down well with them. He could go on a mazy run like he did against Tottenham."

At Birmingham Hayden Mullins looked after him and, when Morrison returned to West Ham, Mark Noble and Kevin Nolan, who famously took Andy Carroll into his house and under his wing when the striker was experiencing off-field problems at Newcastle, urged him not to throw his career away.

For the time being there seems little chance of that happening. Morrison scored six goals in pre-season and is West Ham's top scorer with four goals in all competitions. He has also been called up to the England Under-21 squad for the first time.

Allardyce had planned to ease Morrison in gently, perhaps giving him 20 minutes here and there out wide, but has found him impossible to ignore. Morrison has started the past four matches in central midfield and is playing with a swagger befitting someone with his first name on his shirt. What is remarkable is that even though he has not played much football, he looks like a seasoned professional: aside from the breathtaking tricks and the way he goes past players as if they are not there, just as impressive is the way he weights his passes, his appreciation of space and his clinical finishing. Football is not meant to look this easy.

"He's a tricky player, he megs a lot of people," James Tomkins says. "He's megged me about a hundred times so I'm getting used to it. But that's what you've got to do, you've got to go easy on him in training. He's a good talent."

Now the challenge is to keep Morrison grounded. West Ham are fiercely protective of him, determined to keep Morrison away from the media spotlight. This new chapter in his life is only just beginning. "We've got to keep his feet firmly on the ground and watch out for head swelling," Allardyce said. "We don't want to be changing the size of our doors because he can't get his head through them." Although, as Tottenham found, Morrison is quite good at finding a way through.