THIRD ROUND LEADERBOARD:
-16 P Mickelson (USA), N Watney (USA) -12 J M Singh (Ind), C Villegas (Col)
-11 S Hoffman (USA), S Kjeldsen (Den), J Furyk (USA), K Perry (USA), A Quiros (Sp)
-10 R McIlroy (NI) -9 L Donald (Eng) -8 P Harrington (Ire) -7 T Woods (USA), E Els (SA), O Wilson (Eng), P Casey (Eng), I Poulter (Eng)
Watney had to work hard late in his round to stay in contention
American duo Phil Mickelson and Nick Watney hold a four-shot lead over the rest of the field going into the final round of the WGC-CA Championship.
Watney had four birdies in his opening six holes but had to save par on the 18th to stay on terms with Mickelson.
Northern Ireland teenager Rory McIlroy remains in contention on 10 under, six shots behind the leading pair.
World number one Tiger Woods hit his best round of the week - a 68 - to move up the leaderboard to seven under.
The 33-year-old American, playing his best golf since returning from an eight-month injury lay-off, birdied the par-five 1st before failing to convert a series of tricky birdie chances.
Watney took over at the top of the leaderboard from second-round leader Mickelson after racing to the turn in a four-under 32.
Mickelson, who is chasing a win to help him close in on the number one spot in the world rankings, struggled on the front nine, sending his tee shot into the water at the 4th and three-putting for a bogey on the 7th.
Watney suffered his first bogey of the tournament at the 11th before birdies at the 12th and 16th put him back into contention.
Mickelson recovered his composure on the back nine with three birdies in a row from the 12th and although he drove left at the 17th, eventually ending up with his third bogey, he parred the last to finish with a 69.
But he refused to consider that the final round would be a two-horse race between him and Watney.
"We've seen a lot guys shoot seven, eight-under par. Guys that are three or four shots back, if they shoot that, they can get right back into contention," he said.
"So Nick and I need to play well to separate ourselves from the rest of the field and if we are able to do that it could turn into a match-play situation.
"But right now I don't think we can approach it like that."
McIlroy, bidding to become the youngest winner on the PGA Tour, was one off the lead at one stage before bogeying three of the last five holes.
Ahead of McIlroy and four shots back on the leaders in a tie for third are Jeev Milkha Singh of India and Colombia's Camilo Villegas, with Denmark's Soren Kjeldsen and Spain's Alvaro Quiros joining Americans Jim Furyk, Charley Hoffman and Kenny Perry on 11 under.
Perry fell away after a nightmare double-bogey on the par-three 13th.
His tee shot hit a rake and raced across the green into the rough. As he set up for his next stroke the ball moved forward and cost him a one-shot penalty.