Wayne Rooney said, on Wednesday, that he was worried about the strength of the squad.
He hinted that the club was falling behind its rivals in terms of attracting star players. Some say it's because Ferguson has not been able to spend lots of money in the transfer market.
Lots of fans have been concerned by the amount of money the club owes since the Glazer family took over in 2005.
They believe the Glazers haven't given Sir Alex enough money to bring more star players to Manchester United.
Some fans have even started a campaign to get the owners out. They encourage supporters to wear green and gold to show they want a change of ownership.
Wayne Rooney's contract runs out at the end of the 2011/12 season. If United decide to sell him before then they could get a big transfer fee. If not Rooney would be able to go to his next club for free.