Graeme McDowell shot a brilliant second round 66 to take a three stroke lead at the halfway stage of the Chevron World Challenge.
The 2010 winner, two shots behind Nick Watney overnight, surged ahead with a seven birdie, one bogey round at Sherwood Country Club.
At nine under par the Northern Irishman is three clear of Americans Keegan Bradley, Jim Furyk and Bo Van Pelt.
Tournament host Tiger Woods lies one further back on five under, ahead of Watney and Rickie Fowler.
England’s Ian Poulter shot a level par 72 but after an opening 73 is ten shots back and one of only three players over par in the 18-man field.