Barcelona captain Andres Iniesta says the players are in the dark over the injury suffered by Lionel Messi during Wednesday's 1-1 draw with Atletico Madrid.
The Argentina star was forced off just before the hour-mark after failing to shake off the effects of a tangling with Diego Godin, with initial reports suggesting he may have sustained a recurrence of the groin injury he suffered on international duty this month.
Angel Correa struck an equaliser two minutes after Messi's exit to compound a miserable start to the second half for Barca, who saw Sergio Busquets depart the field not long after half-time.
Iniesta, who set up Ivan Rakitic to head in the opening goal, says Busquets was struggling with illness but admits there is more uncertainty over Messi's problem.
"I don't know what's up with Messi, we'll have to see," he said after the match. "Hopefully it's not too serious. Busquets has a touch of the flu.
"These are things that happen, there's nothing you can really say. It's just unfortunate."
Iniesta concedes there was a degree of frustration at the final whistle that Barca could not hold on to their lead, especially with Real Madrid having been held to a 1-1 draw by Villarreal earlier on Wednesday.
"We played a very complete game, Atletico are always difficult to play, they defend very well," he said.
"The corner [before the goal] worked well, but it's frustrating to drop two points at home.
"It's a game that's decided by very small details. We could maybe have had more chances but Atletico put in a huge effort."