Pep Guardiola, the Barcelona coach, entered hospital with severe back pain and it is unclear yet when he will be discharged, the club said.
The coach had been in obvious discomfort when he attended Barcelona's 1-0 away victory over Valencia the previous evening and the pain later forced him to seek hospital treatment, it said.
"Guardiola was admitted in the early morning to a Barcelona hospital centre to treat back pain that has afflicted him for two weeks," the club said a statement on its web site. The hospital would treat and review his "acute" back pain, it said.
The development of his condition will decide when he is discharged, the club said.
As a result Guardiola will miss the squad's training session later in the day, it said. He had also been forced to skip training on the eve of the Valencia clash.
Lionel Messi scored the goal in Valencia that pushed Barcelona 10 points clear of rivals Real Madrid at the Spanish first division summit.
It handed Guardiola his first ever victory at the Mestalla, the only top-flight venue where he had failed to secure three points.