The highly rated 17-year-old made an impressive cameo appearance against Al-Hilal earlier this week, catching the eye sufficiently to provide further reinforcements in the Reds' senior squad.
"We brought young Welbeck into the squad for the trip to Saudi and he did very well. He will stay with the first team squad now," revealed Ferguson to manutd.com. "He's no doubt a Manchester United player, the boy, but he's only young, he's only 17. He needs time, like they all do, and he needs a bit of strength.
"But he's got a lot of marvellous things about him. He's a local boy, which is nice too, it's nice to get a local boy in."
Sir Alex also revealed that Welbeck's ascension to the first team setup has been hastened by United's shock exit from the FA Youth Cup.
"We knew about him, but while the Youth Team were still in the FA Youth Cup, we left him alone, but now they're out of the Cup he joins us," he said.
"He'll be a nice wee addition, I think he'll get involved once or twice as the season goes on."