Barcelona will be without midfielder Thiago Alcantara for an estimated eight weeks after he suffered a knee injury in the 3-2 victory over Sevilla on Saturday.
The Catalan club confirmed on Sunday that Thiago, 22, who missed Euro 2012 and the Olympics with a shin injury, suffered a medial ligament tear in his right knee during the previous night's game.
The Spain international replaced Sergio Busquets as a second-half substitute, helping Barca overturn a 2-0 deficit. He actually hurt his knee in a challenge while his side were losing 2-1, but with Tito Vilanova having already made his three changes the player asked to stay on the pitch.
And Barcelona sporting director Andoni Zubizarreta, who was boarding a plane to Lisbon on Monday morning for the Champions League game against Benfica on Tuesday, says that the injury is a blow, given the player's impressive form.
"It is a huge misfortune," he said. "Thiago had returned well and he was a player who gives us lots of options."
Thiago played a key role in Cesc Fabregas' equaliser to level the scores at 2-2 on Saturday, although Sevilla coach Michel protested that the youngster had used his hand to win back possession.
But Zubizaretta says claims that referee Mateu Lahoz had favoured Barcelona in the game were not worth commenting on.
"I am not going to start judging refereeing mistakes or favours because they have a very difficult job," he said. "We are living at time when people draw absolute conclusions from things which happen in a second."
Barcelona face an important week with the trip to Benfica being followed by Real Madrid at the Camp Nou in La Liga on Sunday, where they will be hoping to improve on their current eight point La Liga advantage over their rivals with a victory.
"It is a very important week because we are playing in the Champions League," Zubizaretta added. "But the really big weeks, where we want to be, are not until May."