Miami - Australian Adam Scott, the 2013 Masters winner, fired a six-under par 66 Friday to seize a two-stroke lead after the second round of the World Golf Championships Cadillac Championship at Doral.
Scott fired eight birdies, the last three of them in a row starting at the par-3 15th, to leap into the lead on 10-under 134 after 36 holes at Doral.
Northern Ireland's Rory McIlroy, dreaming of the completion of a career Grand Slam with a victory in next month's Masters, shot 65 to share second on 136 with American Dustin Johnson, the defending champion who carded a bogey-free 64.
England's Danny Willett was on 137 with two-time Masters champion Bubba Watson and fellow American Charley Hoffman on 138 and England's Paul Casey was joined by Phil Mickelson on 139.
Scott opened with back-to-back birdies, took a bogey at three and had back-to-back birdies again at six and seven. He birdied the par-5 12th before another bogey at 14 only to finish with a flourish to grab the lead.
Having ended a near two-year title drought at the Honda Classic on Sunday, Scott could become the first player to win in back-to-back weeks on the US tour since Billy Horschel in 2014 at the BMW Championship and Tour Championship.
"I think overall, it was just a lot of good stuff," Scott said. "Enough quality shots and enough quality putts to negate a couple of mistakes out there. But they can easily happen on this golf course.
"So I'm glad there was enough of the good stuff to keep me up on top and kind of setting the pace after halfway."
McIlroy opened with a birdie but took his lone bogey at the second hole. He ran off four birdies in a row from the fifth through the par-5 eighth hole, then birdied the 12th, 15th and 18th to nab a share of second.- Eliminating mistakes -
McIlroy needed just 23 putts, 10 fewer than he had on Thursday.
"I just needed to play a round without as many mistakes," McIlroy said. "The birdies were there. I've been making birdies. That's not been the problem. It's eliminating these mistakes that I've been making, and to play a round with only one bogey was really nice.
"I'm probably happier about that than the eight birdies I made out there to be honest with you, because the last few rounds, it's just been great shots mixed with poor shots."
Johnson birdied the second, sixth and eighth holes on the front nine, began the back side with two more birdies and birdied the par-3 13th plus 16 and 17 to secure his share of second place without making a bogey.
"I think the golf course is fantastic. It's in great shape," Johnson said.
"The greens are perfect. But it's not an easy golf course... You can't take it easy anywhere out here."
World number one Jordan Spieth had four birdies and four bogeys in an even par 72 that left him tied for 12th at three-under.
Overnight co-leaders Marcus Fraser and Scott Piercy both signed for 77s to slip down the leaderboard.
Leading second-round scores on Friday from the World Golf Championships Cadillac Championship at Doral (USA unless noted, par-72):
134 - Adam Scott (AUS) 68-66
136 - Rory McIlroy (NIR) 71-65, Dustin Johnson 72-64
137 - Danny Willett (ENG) 68-69
138 - Charley Hoffman 68-70, Bubba Watson 69-69
139 - Paul Casey (ENG) 71-68, Phil Mickelson 67-72
140 - Charl Schwartzel (RSA) 73-67, Anirbar Lahiri (IND) 70-70, Jason Dufner 68-72
141 - Harris English 71-70, Chris Wood (ENG) 72-69, Jimmy Walker 69-72, Smylie Kaufman 71-70, Rickie Fowler 70-71, Andy Sullivan (ENG) 71-70, Bernd Wiesberger (AUT) 72-69, Jordan Spieth 69-72, Justin Thomas 75-66
142 - Brooks Koepka 71-71, Henrik Stenson (SWE) 71-71, Russell Knox (SCO) 71-71, Jamie Donaldson (WAL) 70-72, Danny Lee (NZL) 71-71
143 - Billy Horschel 72-71, Marcus Fraser (AUS) 66-77, Scott Piercy 66-77