Spanish football has been hit by an epidemic of injuries that has put a string of key players out of action for up to six months. A high proportion are knee injuries, in particular damage to the cruciate ligament. Of the 44 serious injuries suffered in La Liga this season, 20 have to do with the knee, 14 of them cruciate ligaments.

Theories are many, with people blaming the pitches, boots, studs, inadequate warm-ups and what players do in their spare time. Manuel Pellegrini, the Villarreal coach, said: “These knee injuries are very worrying. This just isn’t normal and it’s time we all sat down together and tried to figure out what’s going on.”

Genaro Borras, who heads the Spain medical team, believes that there are three key factors. “We don’t pay enough attention to minor injuries that then trigger more serious ones, the sheer number of fixtures and the reluctance of referees to punish strong tackles,” he said. Guillén attributes the rise of knee injuries to shortcomings in training. “They’ve got too much muscle,” he said. While it is possible to build up muscles, the ligaments do not get any stronger, creating an imbalance. “I’m experimenting with an elastic knee bandage and a series of preventative exercises in the hope of ending the epidemic of this type of injury.”