United are three points clear of Chelsea with three games remaining, but would effectively clinch the title if they win at Stamford Bridge, given their superior goal difference.
Ferguson said Vidic had remained under observation until late in the night on Tuesday.
Vidic's situation improved on Wednesday but he was still not fit enough to play in the Champions League semi-final, first leg.
Ferguson said after the Barcelona match: "He's back at the hotel taking plenty of fluids and had some soup this afternoon.
"That's promising, so let's hope we can get him there on Saturday.
"He will be desperate to play and if we do get him there it will be a bonus to us."
In Vidic's absence, the manager opted for a successful pairing of Wes Brown and Rio Ferdinand in central defence.
United stayed in Barcelona on Thursday for a warm-weather training session before returning to Manchester ahead of the Chelsea match.