The day after being given a five-match touchline ban, over comments made about a referee, the Manchester United manager, Sir Alex Ferguson, has been given more bad injury news affecting his defenders.

Rio Ferdinand could miss the rest of the season and John O'Shea and Rafael da Silva will be out for five and three weeks respectively, with hamstring injuries.

Ferguson has decided not to appeal against the five-match ban that he was given by the Football Association on Wednesday, but the Manchester United manager is still clearly not happy with the situation. Ferguson learned of his touchline ban – which was imposed in response to comments he made about the referee Martin Atkinson after United's 2-1 defeat at Chelsea earlier this month – after a disciplinary hearing. He had vowed to defend himself strongly.

"It is disappointing," he said. "[Football] is the only industry where you can't tell the truth. But it is in the past now."

Ferguson has a number of injury problems. He suggested on Thursday that Ferdinand could face a longer spell on the sidelines than was envisaged when he suffered a calf injury in the warm-up before United's Premier League defeat at Wolves on 5 February.

"Rio has been out for a few weeks now," said Ferguson. "We are not looking at this as a short-term situation. He has not started training yet. We will be lucky to get him back for some part of the season."

Ferguson confirmed that the Republic of Ireland defender O'Shea, who limped out of Tuesday's Champions League win over Marseille, will be out for five weeks, with a hamstring injury. Ferguson, who said O'Shea's injury was "not a good one", will also be without the Brazilian defender Rafael for up to three weeks, thanks to another hamstring injury.

United's captain, the centre-back Nemanja Vidic, will miss Saturday's match against Bolton Wanderers at Old Trafford, thanks to a calf injury.

"Vidic won't make it," said Ferguson. "He is showing good recovery for this week and should be OK after the international break but not enough for Saturday."

Ferguson has only four fit defenders – Fábio da Silva, Chris Smalling, Wes Brown and Patrice Evra – so he may be forced to take a risk with the fitness of the Northern Ireland international Jonny Evans, who has not played since standing in for Ferdinand against Wolves. Evans suffered an ankle injury in training shortly afterwards.

"It has been a bad spell for us," said Ferguson. "Only a few weeks ago we had every defender fit and things were looking great. It has all just fallen apart in the last week or so. Hopefully Jonny Evans may be fit for Saturday, even if it is a bit of a risk. He has trained all week but he has been out for such a long time."