Alex Ferguson challenges Danny Welbeck to score 20 goals next season

Best moments... Maybe, just maybe When England went behind against Sweden most fans were thinking they'd seen this before. So when Danny Welbeck scored the winner we couldn't believe our eyes. From the moment Theo Walcott came on (Getty Images)

Sir Alex Ferguson has challenged Danny Welbeck to break the 20-goal barrier to prove he can be a top-class striker for Manchester United.

Although there have been sporadic claims of interest from United in Robin van Persie, who has decided not to renew his contract with Arsenal, it rather overlooks Welbeck's impressive development.

Tipped by Ferguson as an outsider for England's 2010 World Cup squad, the 21-year-old took slightly longer to make his mark than his manager thought.

For it was this summer, at Euro 2012, that Welbeck announced his arrival on the international stage, fending off Andy Carroll to become England's number one target man.

Welbeck started all four games in Ukraine, scoring a spectacular winner against Sweden in Kiev, doubling an England tally that began the previous month with a well-taken winner against Belgium.

However, when he reports for duty at United's Carrington training complex later this month, Welbeck faces an even more formidable challenge, living up to his manager's high expectations.

And for that he will need to increase his output from the 12 goals he scored last term, nine of which came in the Premier League.

"Danny can be a top player but obviously he will have to improve his goalscoring," said Ferguson.

"He got nine goals last season but if you are going to be a top striker you have to get 20 or above.

"I think he will do that."

Brought up in the same Longsight district of Manchester as Wes Brown, United have taken a keen interest in Welbeck from a very early age.

It is a good job too as it allowed more thorough treatment of injuries that otherwise might have halted his progress.

"He's always had growth spurts and all little things like weak knees and weak thighs. It was happening all the time," said Ferguson.

"So we fostered him from the age of nine right through that period when he was developing."

And, for defenders at any rate, the nightmare is that Ferguson does not feel Welbeck has completed that physical development yet.

"He's not got his full body yet," he said. "There's a lot of growth in him yet.

"At 6ft 3in, I don't think he'll get taller, it will go the other way, and he is very powerful already.

"He's got good movement and courage, plus confidence on the ball.

"And he showed maturity at the Euros by playing three games in seven days, which he has certainly not done for us before."

In fact, the only difficulty United are encountering with Welbeck just now is the frustrating amount of time it is taking to negotiate a new contract for the striker, whose present deal expires in 12 months' time.

It had been hoped negotiations would be concluded before the new campaign gets under way.

However, Ferguson has been unable to offer any meaningful update.

"It's difficult to say where we are with that at this moment in time," said the Scot.

Yet, if Welbeck headed off on holiday buoyed by his international experience, for strike partner Wayne Rooney it was another summer of frustration.

Once again at a major tournament, Rooney failed to do himself justice, missing England's opening two games through suspension, then producing below-par displays against Ukraine - even though he scored - and Italy as Roy Hodgson's men crashed out in the quarter-finals.

Not that Ferguson was entirely surprised.

Having worked with Rooney for eight years now, he always felt that lengthy gap between his star man scoring for United in their last-day win over Sunderland and his opening salvos of Euro 2012 might present an insurmountable barrier.

"I always thought it was difficult," said Ferguson.

"We know him better than anybody and he needs a lot of football.

"Wayne's a stocky lad. If he misses a couple of games, it takes him three or four to come back and he didn't play from his last game (for United) on May 13 until the third game of the Euros more than a month later."

In fact, Rooney did manage a 37-minute friendly appearance against Belgium in between.

However, when England needed a big performance from their talisman against Italy, Ferguson detected tiredness from his outing against Ukraine.

"He didn't look as sharp as normal," said Ferguson.

"It is very hard to play two big games in four days."

Ferguson sees no long-term problem though.

Neither does he feel Rooney was placed under too much pressure in an era when star men are scrutinised like never before.

"It's a fact of life," he said.

"I read an article that Argentina have never taken to Messi. Then he goes and scores a hat-trick against Brazil with that incredible third goal.

"People were saying Spain weren't the force they were, then Xavi produces the kind of performance he did. It was brilliant.

"Great players have to deal with these things."

PA