Barcelona are choosing not to reveal the extent of Andres Iniesta's hamstring injury in the hope the midfielder will be able to feature in the Champions League game against Chelsea next week.
Iniesta, 33, was forced off in the first half of Barca's win against Atletico Madrid on Sunday with the problem and was unable to train with his teammates on Wednesday.
Barca, who usually will share the length of time an injured player is expected to miss, have only said that Iniesta's "recovery will determine when he returns to action."
The midfielder will not feature at Malaga on Saturday in La Liga but there remains a very slim chance he will be available for Chelsea's visit to Camp Nou next Wednesday.
Lionel Messi cancelled out Willian's opener when the two teams drew 1-1 at Stamford Bridge in the first leg of their round-of-16 tie last month.
Philippe Coutinho would be the obvious replacement should Iniesta not recover in time, but the Brazil international is cup-tied having already played for Liverpool in the competition earlier this season.
That leaves Ernesto Valverde with a choice between Paulinho, Andre Gomes and Denis Suarez to fill in alongside Ivan Rakitic and Sergio Busquets.
"Iniesta is a unique player, a little like Messi, so it's difficult to find a player who can replace him," Valverde said on Sunday when asked who could take the Spain international's place.
"He is unique in the world in terms of the characteristics he has. We will have to see the extent of the injury. He carried on playing at first so we thought it wasn't too bad, but we're not sure."
Nelson Semedo is the only other Barca player currently sidelined. The Portugal right-back will definitely miss the Chelsea game, meaning the option of moving Sergi Roberto back into midfield is unlikely.
However, there's better news for Valverde in the form of Gerard Pique, who trained as normal on Wednesday despite struggling with a knee injury during the last month.
Pique was one of 12 first-team players who trained at the Ciutat Esportiva, while another eight players are in Lleida ahead of the Catalan Super Cup game against Espanyol.