With Saha increasingly unreliable and Ole Gunnar Solskjaer retired, United would be short in attack if Wayne Rooney or Tevez picked up an injury and Ferguson does not want to jeopardise his side's chances of silverware.
Fergie has asked the club's owners if money is available in January and was given a positive response. Huntelaar's agent has admitted that this is likely to be the Dutch star's last season at Ajax.