Manchester United's Brazilian midfielder Anderson will miss the rest of the season after rupturing his cruciate ligament in the comeback game which followed a period of doubt about his Old Trafford future.
The blow creates an immediate problem ahead of United's Champions League tie with Milan on Tuesday week with Michael Carrick already suspended. Anderson sustained the injury during Tuesday night's 3-0 win over West Ham.
"When you see cruciate injuries it is usually something simple," Ferguson said. "It is a bad bit of news for him. He had just come back into the first-team after being out for a few weeks."
His doubts about his United future seem to have been shared by the club. They were understood to have been receptive to an approach from Lyons to take the player on loan in January but his wages proved an obstacle. The 21-year-old will undergo treatment in Portugal.
"Hopefully, six months [out] should have him about right for the new season," Ferguson said.