Manchester United manager Sir Alex Ferguson is optimistic Rio Ferdinand will only be sidelined for weeks, rather than months.
Ferdinand has endured an injury-plagued campaign and has missed United's last four matches with what was thought to be a calf complaint.
However, the Premier League champions have traced the centre-half's latest injury troubles to a long-standing back problem, which reports suggested could keep Ferdinand out until the New Year.
The England international will miss Saturday's game against Everton, but Ferguson believes the 31-year-old could return within a fortnight.
"It is back related," said Ferguson.
"We are not putting a timescale on it, but it is not a situation where we are saying it will be months, it might be a couple of weeks or it might be a few weeks but that is it."
Ferguson is also unsure whether Jonny Evans will be fit to face Everton after the youngster picked up an injury on international duty with Northern Ireland.
He added: "We're fighting hard to get Evans available, but he's not trained yet. We'll see how he goes today [Friday]."
John O'Shea is also a defensive worry after suffering a thigh injury during the Republic of Ireland's controversial World Cup play-off exit at the hands of France on Wednesday night.
Captain Gary Neville is suspended and Fabio da Silva is out, so Ferguson may be forced to partner Wes Brown with the fit-again Nemanja Vidic and select Rafael da Silva and Patrice Evra at full-back.