Barcelona midfielder Sergio Busquets was forced off with an ankle injury during his side's 4-0 win at Eibar on Sunday.
Busquets went down after a challenge from Gonzalo Escalante with less than 10 minutes on the clock and almost immediately summoned for the stretcher.
The club have since confirmed that the midfielder has sprained ligaments in his right ankle and he will undergo tests at the training ground on Monday to determine the severity of the injury.
Speaking after the game, Luis Enrique suggested the injury is not as bad as had been initially feared.
"Having seen how Sergio got injured, the best news is it doesn't seem as serious as we expected," the Barca coach said in his postgame news conference.
"It will be a big problem [to not have him available] but we have solutions and options in place so that we don't have to notice when we're missing players."
With midfielders Andres Iniesta and Rafinha already sidelined with calf and hamstring problems, respectively, Luis Enrique will hope Busquets is not kept out for too long.
Ivan Rakitic took his place as Barca's holding midfielder at Ipurua but there are few natural replacements for him in the squad.
Javier Mascherano is an option, while Rakitic and Andre Gomes have both covered the position before.
Busquets has started 17 of the side's 19 league games so far this season and has been an ever-present since breaking into the side under Pep Guardiola almost a decade ago.