Malaga says forward Julio Baptista will be sidelined four to six weeks by a knee injury.
Medical tests on Friday revealed the Brazil player tore his meniscus and suffered a sprain in his right knee after a training ground accident earlier this week.
The Spanish club says Baptista will undergo surgery "in the next few days."
Baptista, who previously played for Sevilla and Real Madrid, has scored two goals from five appearances since arriving on loan from AS Roma in January.
Malaga is last in the table going into Sunday's game against Villarreal.