Spain's Rafael Nadal grimaces as he walks on court while preparing to serve to Croatia's Marin Cilic during their men's singles quarter-finals match on day nine of the Australian Open tennis tournament in Melbourne on January 23, 2018. World No.1 Rafael Nadal retired with a leg injury handing Marin Cilic passage into his second Australian Open semi-final. Pic/AFP

World number one Rafael Nadal faces three weeks out after being diagnosed with a torn inner hip muscle during his Australian Open quarter-final defeat, his management said Wednesday. The 16-time Grand Slam champion had a scan in a Melbourne hospital after he retired early in the fifth set of his match with Croatia's Marin Cilic on Tuesday.