The Scotland international midfielder has missed nine matches after being floored by a virus in early March.
But he has been training for more than a week now - and United boss Fergie hopes to have him back by the end of the month.
The Champions League semi-final at Schalke next Tuesday may come too soon.
But United then face title rivals Arsenal and Chelsea in the space of a week - with the second leg against the Germans sandwiched in between.
Fergie said: "Fletcher is back in training, he's not doing a lot but has put the weight back.
"He's had a terrible virus. It's one of those energy-sapping viruses that you can get and he lost a bit of weight.
"But that weight is back on again now and we'll look forward to getting him back."
The United boss said last week that Fletcher was 'a couple of weeks away' - putting the trip to Germany or the Emirates on Fletcher's horizon.