Rangers and Northern Ireland striker Kyle Lafferty has been ruled out for up to seven weeks with a hamstring tear.
And Steven Whittaker is awaiting a specialist report on a groin injury that is also likely to leave the defender on the sidelines for weeks.
Rangers boss Ally McCoist said: "It's not particularly good news for Kyle.
"He looks to have a tear in the hamstring and all indications were that was going to be the case judging by the way he pulled up."
Lafferty left the pitch on a stretcher after just nine minutes of Monday's Scottish Premier League win over Motherwell.
"At this moment, he is on crutches and we think probably six or seven weeks I'm afraid," McCoist told his club website.
Lafferty's absence comes amid speculation that strike partner Nikica Jelavic could be the subject of bids from English clubs during the January transfer window.
The Croatia striker had himself missed the 3-0 win over Well through injury.
"Jelavic is a little bit better," said McCoist. "I spoke with him and the groin injury is not as bad as it was.
"But it's too early to say whether he will be available for our Scottish Cup tie at Arbroath."
The versatile Whittaker has missed Rangers' last two games and will travel to Manchester next week to have his injury examined further.
"Steven Whittaker is going down next Tuesday or Wednesday to see the specialist regarding his groin problem and it will be determined then if he needs surgery," said McCoist.
"If there is anything needing done then hopefully it will be done immediately and we can get him back as quickly as possible."
Kirk Broadfoot, who would be the natural replacement for Whittaker at right-back, is himself an injury doubt for the match at Gayfield.
"Kirk Broadfoot is still struggling," added the manager, who will also have to do without midfielders Steven Davis and Lee McCulloch through suspension. "His leg is heavily iced."