Ferdinand has not made an appearance since suffering a calf problem in the warm-up prior to the Barclays Premier League defeat at Wolves at the beginning of February.
So slow had been the 32-year-old's progress that Ferguson had raised doubts over his ability to get back on the pitch before the end of the season.
Bouncing back: Ferdinand's return to fitness has taken less time than expected
However, Ferdinand has resumed training this week and, so far, come through without a reaction.
It leaves Ferguson with a dilemma about whether to push Ferdinand through another session tomorrow - when his team-mates are tackling West Ham at Upton Park - in the knowledge that if he comes through without a hitch, he could be rushed back to face Carlo Ancelotti's men.
'Rio has started training,' said Ferguson. 'He has only been training two days and then just a light session today.
'I have to decide whether we bring in him tomorrow, or give him a day off and start him on Wednesday again. 'He is more likely to be fit for Fulham.'
Case for the defence: Smalling is likely to line-up alongside Vidic this weekend
Yet Ferguson may ultimately conclude it is worth taking a gamble given none of his other injured defenders will be back to face Chelsea, whilst a few may be available for Fulham.
Rafael, John O'Shea and Wes Brown could all tackle Mark Hughes' men. But none of that trio will make the trip to Stamford Bridge, when Jonny Evans will be available as he serves a three-match domestic ban.
None of this helps his team selection tomorrow, when Ferguson accepts filling the right-back slot is going to be a major issue.
'We have to solve that and find the right solution,' he said.
It seems almost certain Brazilian Fabio will fill the void, with Chris Smalling partnering skipper Nemanja Vidic in central defence. At least Ferguson finally has options in midfield.
Park Ji-sung could make his first start since he left for Asian Cup duty in Qatar, whilst Anderson is likely to be on the bench at Upton Park after recovering from a knee injury it was initially suggested would rule him out for the season.
However, Darren Fletcher is still troubled by a virus, whilst Owen Hargreaves' United career now looks to be at an end following the shoulder problem he picked up in training.
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