U.S. Open champion Rory McIlroy\'s \'slim hopes\' of overhauling world number one Luke Donald and capturing the European Tour season-ending Race to Dubai title are being hampered by a long-standing virus.The Northern Irishman, who won the Hong Kong Open on Sunday to keep alive his bid to topple money list leader Donald, attended a Dubai hospital on Monday for tests on the stomach bug he picked up at the end of October while competing in China.\"I won\'t get the results back until later on this week,\" he told reporters on Tuesday. \"I picked up a virus and my white blood cell count was very low, so the tests were to see if it\'s back up again.\"McIlroy will claim the European Money list for the first time if he wins this week\'s $7.5 million Dubai World Championship and Donald finishes in a tie for ninth with at least two players, but the illness is hampering his preparations.\"I\'m not energy-wise where I want to be, but I took a day off yesterday and took it easy. I\'m going to play the pro-am today and practise and I\'ll probably take another day off tomorrow, maybe hit a few balls,\" McIlroy said.After finishing in a tie for fourth in the WGC-HSBC Champions event in Shanghai last month, McIlroy went holidaying with his girlfriend, world number one tennis player Caroline Wozniacki, in the Maldives and then Dubai.However, McIlroy was feeling so unwell in the Maldives he visited a hospital on three separate occasions to be put on an intravenous drip.