Barcelona captain Carles Puyol appears set to miss six weeks of action, starting with this weekend's La Liga clash with Real Madrid, after dislocating his elbow against Benfica.
Puyol, 34, landed awkwardly on his arm in the latter stages of Barca's 2-0 Champions League win and the seriousness of the injury was immediately evident, with the defender rushed to hospital for treatment.
The Spain international returned to Catalonia with his team-mates overnight and will undergo further tests on Wednesday. Initial reports in the local media suggesting the defender will now face six weeks to three months on the sidelines.
Although Puyol himself tweeted from his hospital bed to thank fans for their support and medical staff in Lisbon for the treatment he received, the injury dampened Barcelona's celebrations of a victory which sees them top Group G with six points from their first two games.
Boss Tito Vilanova said that a run of bad luck for Puyol, who has already overcome a fractured cheekbone and a knee ligament injury this season, was stretching his side's defensive resources.
"These are injuries which happen in football, but not very often and they are all happening to him," Vilanova said. "It is a blow because he is a very important player and because it will oblige us to keep playing players who need a rest.
"[Javier] Mascherano has played 14 consecutive games. We hope to get [Gerard] Pique back, but maybe not for the Clasico. We also have [Marc] Bartra."
Mascherano - whose centre-back partnership with new signing and fellow converted-midfielder Alex Song has looked rocky in recent La Liga games - said the injury had taken any gloss off the three points earned.
"We are in a good moment but what happened with Puyol is a huge blow," Mascherano said. "We count on him, he is so important for us. You cannot explain it. With the knee he had been spectacular, but that is the way it is. It is annoying and makes you not want to celebrate at all."
Barca goalscorer Cesc Fabregas said the injury had affected those who saw it on the pitch but Puyol's mental strength would help him return quickly.
"It left you feeling bad," Fabregas said. "He is a fundamental player. He is very strong. He came back from a few weeks out and is injured again. But he is the mentally strongest guy I know."