Ageing South China defender Ku Kam-fai has been thrust into the firing line for tonight's FA Cup semi-final against Happy Valley at Mongkok Stadium. Ku has been called up to replace injured Brazilian defender Jose Ricardo Rambo in the Caroliners' match against their fierce rivals, whom they meet again in Sunday's First Division league championship play-off. South China's Brazilian coach, Casemiro Mior, decided to field 38-year-old Ku after Ricardo injured his left knee in training on Tuesday. Ku is no stranger to the big occasion, having led South China to numerous accolades and Mior said he had faith in the former South China skipper. 'Ku will do fine. It's unfortunate that Ricardo can't make it,' said Mior. 'It's going to be a tough game for us because Happy Valley are a very strong side and they will trying their best to beat us. 'We have two very tough matches against Happy Valley and nothing less than our best will see us through.' South China will be virtually at full strength, with the Caroliners relying on Au Wai-lun and Ricky Cheng Siu-chung to spearhead their attack. Happy Valley will also play a full-strength team tonight with only one minor change. Bosnian striker Alen Bajkusa will have a full game, replacing English veteran forward John Moore in attack. Happy Valley coach Chan Hung-ping said he expected an extremely tough match against the Caroliners. South China and Happy Valley have played each other five times this season with the teams winning twice each. Their other, and most recent, encounter ended in a goalless draw in a league match played last month.