It will be a battle of the No. 2 player in the world (Woods) and the fourth-ranked player (Mickelson). The two, never the closest of friends, were partners at last year's Ryder Cup (going 0-2) and have duked it out in the final round before.
At the 2000 Tour Championship, Mickelson became the second player ever to beat Woods when Woods had at least a share of the third-round lead. They played together in the final round of the 2003 Buick Invitational, but Woods bested Mickelson by six and went on to victory.
'I'm looking forward to tomorrow,' said Mickelson. 'I know what a great player he is. I've seen it for so many years. It's fun for me to compete head-to-head with him.'
For Woods, a win on Sunday would allow him to overtake Vijay Singh atop the world rankings.
'Phil's playing great golf, beautiful golf,' said Woods. 'I'll have to shoot another low one. I'm going to have to go out there and post a good, solid number.'
Defending champion Craig Parry carded a 5-under 67 and is tied for third place with Zach Johnson (64) and James Driscoll (67). The trio is knotted at 14-under-par 202.
Singh shot a 4-under 68 on Saturday and shares sixth place with Jim Furyk (67) and Jose Maria Olazabal (70) at minus-13.
Those groups will have a lot of work to do on Sunday if they are going to catch Mickelson or Woods.
Mickelson birdied the third, then dropped a shot at four when he missed a 6-footer. The lefthander hit some great iron shots at the next three holes, all resulting in birdies from inside 10 feet. The birdie at seven gave Mickelson a four-shot lead, but Woods closed the gap.
Woods recorded three birdies on the front nine, then hit a 3-wood long of the green at the par-5 10th. He got up and down for birdie, and collected three birdies in a row from the 12th to get within two of Mickelson's lead.
Mickelson played well on the back nine with a tap-in birdie at the 10th. He added another birdie at the 12th to move three ahead, but Woods clawed back thanks to an amazing shot at the reachable, par-4 16th.
Woods' drive at the hole landed flag-high, then rolled 40 feet past the cup. He two-putted for birdie and hit his approach from 151 yards to 4 feet at the 'Blue Monster,' Doral's famous 18th hole.
'No one clapped. We didn't have any clue. I knew I hit it in the direction of the green,' said Woods, referring to his shot at 16.
Mickelson, now with a one-shot lead, missed the green with his tee ball at 16. He pitched 3 feet past the hole and converted the birdie try to extend the advantage to two.
Mickelson struggled with the driver on Saturday to the tune of only four fairways hit. He drove into the rough on the left at 17 and his approach landed in a greenside bunker. Mickelson blasted out to a foot and tapped in for par.
At 18, Mickelson's tee ball sailed right, but he still had a good shot at the green. His second came to rest 15 feet right of the hole, but Mickelson missed the putt. That cost him a three-shot cushion and left him one stroke short of Greg Norman's 1993 54-hole record.
'Fortunately, I was able to shoot 6 under to keep a reasonable pace,' said Mickelson, who has won two of his last three starts on tour. 'I will spend a little more time with the driver. I didn't drive it the way I've been driving it. When I was in the fairway, I felt like I could get at a lot of pins.'
Woods has not recorded a round over par in his 2005 campaign. His swing changes that kicked into effect at the end of 2004 are working and Woods will look to add his second title of the year.
'I found one swing and went with it,' said Woods. 'Everything worked out pretty good.'
Joe Ogilvie (66), Harrison Frazar (68), David Toms (69), Tim Clark (69) and Billy Andrade (72) are tied for ninth place at 12-under-par 204.