Ferguson expects duo to be missing for three to four weeks
O'Shea started on the right of a defence that also included Wes Brown, Chris Smalling and captain for the evening Patrice Evra but had to be replaced before half-time as he injured his hamstring whilst United were on the attack.
His replacement, Rafael, was also taken off half-way through the second half for twin-brother Fabio as the right-back also pulled up with a suspected pulled hamstring and had to be stretchered off.
These latest casualties join Nemanja Vidic in the treatment room as the Serbian was declared injured on Tuesday after a day of speculation as to his condition.
The centre-back picked up a calf injury during the 2-0 FA Cup win over Arsenal on the weekend while Jonny Evans and Rio Ferdinand are also currently sidelined meaning boss Sir Alex Ferguson could have something of a defensive problem against Bolton on Saturday.
Sir Alex Ferguson later revealed in his post-match press conference that Rafael and O'Shea could be out for around three to four weeks, with a reporter even asking if Gary Neville could come out of retirement.