The France forward came on as a substitute for the fourth successive game against Chelsea on Sunday, scoring his second goal of the season from the penalty spot. But Ferguson insists he will continue to use Saha sparingly to guard against the sort of injuries that kept him out of United's abortive chase for the treble at the end of last season.
He said: "We have been cautious with Louis. He has been out for eight months, and our objective has been to ease him back in.
"We are playing a long game here. It's a long season and one panicky move now could mean more trouble later."