The central defender is struggling to recover from a calf injury that has sidelined him for the last three games and manager Alex Ferguson said time was running out for him to prove his fitness for Wednesday's clash with Barcelona in Rome.
"I am hoping Rio will be fit for Sunday," Ferguson told United's website. "If not then he's doubtful for Wednesday. I think he needs a game.
"To go into a Champions League final without playing for three weeks might be a bit much."
United, crowned Premier League champions last week, are expected to field a weakened side for their final league game of the season at Hull, who need a win to guarantee their survival in the top flight, but Ferdinand will be involved if he is fit.
"The plan is for him to start training with the team on Thursday," Ferguson added. "Once he starts on the football training we will have a better idea about his availability for Sunday. So hopefully he will be fit."
The 30-year-old Ferdinand's absence would be a blow for United but Ferguson said the emergence of Jonny Evans eased his worries about the England's defender's availability.
"I'd have no problem with it," said Ferguson. "I wouldn't be bothered one bit about selecting Jonny for the final.
"He has had a fantastic season, the kid. He is 21, and he's much like (Barcelona's) Gerard Pique - they grew up together here. It would be a fitting tribute to our academy if both players played in the final. It would be a nice touch."
NEWS: All white on the night for Reds in Rome
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