Celtic champions Rory McIlroy and Graeme McDowell engineered a two shot lead to put daylight between Ireland's World Cup claim and a chasing trio of golfing powerhouse nations on Saturday. World number two McIlroy and 2010 US Open winner McDowell fired eight birdies in the fourballs third round to card a sterling 8 under 64. They remain top of the leader board on 21 under overall, nudging ahead of the sizzling Teutonic pairing of world number four Martin Kaymer and Alex Cejka, who holed 11 birdies in their ground-making 61. "We made lots of birdies and always on different holes, and I played very well today," said Kaymer. "But obviously you can only play well and be aggressive if you have a partner who is playing very consistent and is always there for you," he added. Germany are tied second with big hitters South Africa and the USA on 19 under overall. South Africans Charl Schwartzel and Louis Oosthuizen wooed the modest crowd with their powerful tees, as the duo carded an impressive 11 under 61 and sunk eleven birdies. The resurgent USA team of Gary Woodland and Matt Kuchar ensured their hands were still within touching distance of the trophy going into tomorrow's fourth round with an 9 under 63. Australia slipped to fifth as Brendon Jones and Richard Green struggled in the wet and humid conditions at the Mission Hills complex, but they still stayed close to the leaders on 18 under overall. Defending champions Edoardo and Francesco Molinari of Italy put themselves back into contention with a 8 under 64 and are tied 7th with Mexico on 16 under overall. England's Ian Poulter and Justin Rose also made heavy work in the fickle conditions, seeing their hopes of lifting the trophy disappear in the steamy atmosphere. They carded two bogeys in their four under 68 and are joint 15th with Zimbabwe on 13 under overall. Home hopes for a fairytale victory were dashed however as China's Zhang Xinjun and Liang Wenchong slipped to joint 17th on 12 under. Sunday's final round of the US$7.5 tournament will see a return to the tricky foursomes alternate shot format.