United flew out on Monday with the pair among just four defenders to travel as manager Sir Alex Ferguson contemplates sending out a patched-up back four against the Italian champions in the first leg of their last 16 meeting on Tuesday.
The Scot is already without the suspended Nemanja Vidic while Gary Neville, Wes Brown and now Rafael are all absent through injury.
Evans limped out of the 2-1 league win over Blackburn at the weekend with a reccurrence of the ankle injury which recently kept him out of action for a month, while O'Shea missed the Rovers clash with a heel injury.
Ferguson is hoping that at least one of them will be passed fit to ease his defensive woes, but if either misses out midfielder Darren Fletcher may be asked to fill in at right-back.
Fellow midfielder Michael Carrick is all too aware of the threat Inter pose and despite the injury crisis is looking forward to the match.
Tough test"Inter are as tough an opponent as we could get right now," he said.
"They are in good form at the top of their league. We are both probably amongst the top four or five in Europe at the moment but that is what the Champions League is all about.
"You have to defeat the best if you want to win."
United's last defeat in the competition came against Inter's city rivals AC Milan two years ago when they were comprehensively beaten at the semi-final stage.
Then, as is the case now, the Red Devils suffered from a shortage of defenders but the England international is confident his side can continue their unbeaten run.
He added: "Going to the San Siro to play Inter is a massive game and a big test for us.
"Over the past two years we have been very consistent in the Champions League.
"We have not suffered any defeats since the last time we went to the San Siro and hopefully we can keep that run going."