Valencia midfielder Ever Banega has undergone surgery for a double fibula-tibia fracture in his left leg, after an accident a day earlier.
Banega, 23, has had an injury-plagued season and missed his side's game away to champion Barcelona because of a knee strain.
He had gone to train alone at Valencia's Paterna training ground on Sunday afternoon. Afterwards, he stopped at a petrol station but forgot to activate the handbrake on his car. The vehicle rolled backwards, smashing his left leg against a pavement.
He underwent surgery at Valencia's Nou D'Octubre hospital. The operation was carried out by specialist Vicente Vila, in the presence of Valencia's club doctor Enrique Gastaldi.
Gastaldi said the operation was a success, but that the Argentine midfielder will be out of action 'for at least six months'.
Banega joined Valencia from Boca Juniors in 2008 but struggled to make an impact at first and was loaned out to Atletico Madrid.
From 2009, however, he has been the fulcrum of the Valencia midfield, when fit.
He was overlooked by Argentina for the 2010 FIFA World Cup finals but played for his country at the 2011 Copa America.
Barcelona captain Carles Puyol is to undergo knee surgery to remove a cyst, the club says.