Third-round leaderboard (par 72)* -18: L Westwood (Eng), L Oosthuizen (SA)* -15: P Mickelson (US)* -14: B Haas (US), E Els (SA), I Poulter (Eng)* Selected others: -13: B Snedeker (US) -12: A Scott (Aus), M Kaymer (Ger) -10 L Donald (Eng), J Dufner (US)SHENZHEN - Lee Westwood carded an 11-under third round of 61 to take a share of the lead at the WGC Champions in Shenzhen.The world number four joined previous leader Louis Oosthuizen, who missed a birdie putt on the 18th, on 18 under, three shots clear of Phil Mickelson.Brandt Snedeker would have had a 59 had he not missed on the last, instead settling for a course-record 60."The course is in great condition and we’re starting to get used to playing it,” said Westwood. "As the week has gone on and we’ve played it and walked it, we’re starting to see lower and lower scores.”The former world number one began the day nine shots off the lead but birdied the opening three holes, the first of 11 in total, as he found some consistency with the putter in China.In contrast, 2010 Open champion Oosthuizen, who shot 63 on Friday to go 16 under after two rounds, paid the price for too many mistakes on the green with a round of two under.Westwood and Oosthuizen will start the final round with three shots between themselves and Mickelson, who is a shot ahead of Ian Poulter, Bill Haas and Ernie Els, the South African briefly sharing the lead before finding water on the 15th.Snedeker is a further one behind, the American setting the course alight playing in the first group of the day.Turning on six under, he holed a "fluke” 75-foot birdie putt on the par-three 13th, with a 25-footer on 17 raising hopes of a magical 59, only for his birdie putt on 18 to creep just wide.England’s Luke Donald is seven shots off the lead after a 69, while compatriot Justin Rose, who could have replaced Northern Ireland’s Rory McIlroy at the top of the European Tour money list with victory, is down in a tie for 26th on seven under.Sweden’s Peter Hanson, another who had the opportunity to overhaul McIlroy, is a further shot back.