Darren Fletcher has 'great challenges ahead' admits Manchester United manager Sir Alex Ferguson United have been linked with Arsenal captain Robin van Persie as well as Sao Paulo's Brazilian winger Lucas Moura. "It is possible we could bring in one more, maybe two more, but more likely one more, but I think we have always done well in terms of getting players at the end of the season," Ferguson added. We've always felt it is the right time - then you don't have to wait all summer. Whenever the European Championship or World Cup is on there is usually a delay in the transfer industry. Now all that is over we are still trying to get maybe one player in. Ferguson unveiled his two new signings yesterday, Shinji Kagawa and Nick Powell. Ferguson monitored Kagawa, 23, after being tipped off by United's Germany scout Peter Braund in October and the Japan international was finally signed for £17 million from Borussia Dortmund last month. Kagawa can fulfil a variety of attacking roles but stated his preference for a central role behind the striker, and Ferguson expects the midfielder to make a significant impact once he has grasped the basics of the English language. He plays in behind the striker, he's very quick and he's got good vision. His goalscoring record over the last two years has been very good from that position," Ferguson said. It was good that he was with a successful team to allow him to adapt to European football. He's a maturing player and in the next few years we'll see that at United. I'm sure over the next few months he'll improve his English or Scottish, whichever is easier, but he won't understand my Scottish when I lose my temper so it doesn't matter. Powell, 18, rose to prominence by helping Crewe to promotion from League Two through the play-offs. Although he thrived as an attacking midfielder, Ferguson expects to use the England Under-18 international in a deeper role. Ferguson said: "He's got a little bit of physical development to go which you'd expect from an 18 year-old but he'll be in the first-team squad. Football always throws up that opportunity for any one person. If they progress and they're good enough I don't have an issue with that. We play young players all the time.