Rangers' £12m striker Tore Andre Flo faces a race against time to be fit for February's double header with Celtic.
The Norwegian striker damaged an ankle on the Gers' winter break trip to Florida.
The former Chelsea striker was taken to hospital after being injured in the friendly with SC Uruguay earlier in the week.
He said: "I twisted my ankle. I thought it was serious when it first happened, but I hope it's not too bad. We'll take another look at it when we come back to Scotland."
Rangers have been hit with a constant stream of injuries this season and striker Billy Dodds and midfielder Ronald de Boer are the latest to be classified as concerns.
Fringe player Peter Lovenkrands damaged a hamstring in the Uruguay game.