Madrid, July 31 -- Real Madrid defender Raul Asencio is set for a spell on the sidelines after suffering a thigh muscle injury that is expected to keep him out until mid-September.

"After tests carried out today, Raul Asencio has been diagnosed with a muscle injury to the rectus femoris in his right leg," the club said on its website.

Madrid did not provide a timetable for the 23-year-old's return, saying only that his recovery will depend on his progress. However, Spanish media reports estimate he will be sidelined for around six weeks.

The injury means Asencio will miss the remainder of preseason under new coach Jose Mourinho and is likely to be unavailable for Real Madrid's opening four or five La Liga matches.

Asencio made 34 first-...