Andres Iniesta has presented Barcelona with an untimely injury headache ahead of important fixtures in La Liga and the Champions League.
The World Cup winner started a meeting with Atletico Madrid on Sunday, but lasted just 35 minutes.
It appeared at one stage as though he would struggle to reach that point, having taken a knock 20 minutes in.
Iniesta was clearly struggling and was forced from the field to undergo treatment.
The 33-year-old felt okay to carry on, but it quickly became apparent that he was going to be unable to see the game out.
He was eventually replaced by Andre Gomes, with a hamstring problem forcing him from the field.
Barcelona were already one goal to the good by the time that decision was taken, with Lionel Messi having recorded the 600th effort of his remarkable career.
Ernesto Valverde told reporters after the game: "Iniesta is a unique player, a little like Messi, so it’s difficult to find a player who can replace him..
"He's unique in the world with the characteristics he has. We will have to see the extent of the injury. He carried on playing so we thought it wasn’t too bad, but we’re not sure… He was playing incredibly."
Any spell on the sidelines will place Iniesta's involvement in key upcoming domestic and continental fixtures in doubt, with early reports suggesting that he could be missing for up to four weeks.
Barca’s ongoing efforts to reclaim the La Liga title will see them face Malaga next weekend, before welcoming Chelsea to Camp Nou for the second leg of a heavyweight Champions League last-16 encounter.
With that contest currently locked at 1-1, Valverde will be eager to have the quality and vast experience of Iniesta at his disposal.
He may, however, be disappointed, with it possible that he will also be without an iconic figure for a game against Athletic Bilbao on March 18.