(Reuters) - World number two Rory McIlroy has withdrawn from the Abu Dhabi Championship after tests on Monday showed he picked up a rib injury in South Africa last week, the European Tour said. The Northern Irishman had intense physiotherapy treatment and took pain-killers over the weekend at the South Africa Open after struggling through much of Friday's second round. The four-time major champion, who lost to Englishman Graeme Storm on the third playoff hole at Glendower Golf Club, will start a rehabilitation program for the stress fracture. More...