Newcastle United legend Malcolm McDonald fears the club risk losing Michael Owen this summer.
"He will have plenty of money, but he may well look at Owen's situation at St James's Park and wonder if he can pick him up on the cheap.
"Because of his goalscoring record, Sir Alex must know that Owen would be a great short-term signing.
"And he must know that Owen, with the support and service he would get at Old Trafford, is more than capable of chipping in with 20 goals.
"This would certainly go some way in compensating for any loss of Ronaldo."