Rory McIlroy refused to blame his new putting technique for a disappointing opening round in the WGC-Cadillac Championship after the new approach initially promised to pay instant dividends.
After missing the cut in the Honda Classic last week, McIlroy changed to a "crosshanded" putting method - with his left hand below the right on the grip - and vowed to stick with it regardless of the short-term outcome, with his bid to complete the career grand slam at the Masters just five weeks away.
The early signs were promising as McIlroy carded five birdies in his first 10 holes on the famed 'Blue Monster' course alongside world number one Jordan Spieth and US PGA champion Jason Day.
But the 26-year-old then three-putted the eighth - his penultimate hole - for par and found water with his tee shot on the ninth, the resulting double bogey meaning he had to settle for an opening 71, five shots behind clubhouse leaders Marcus Fraser and Scott Piercy.
McIlroy had jokingly threatened to throw his putter in the water on the eighth, a reference to last year's incident when his three iron was despatched to a watery grave on the same hole in frustration at an errant shot.
"One club in the water here is enough, I think," the Northern Irishman joked.
Asked about taking 33 putts and holing just one outside 10 feet (a 14-footer on the 17th), McIlroy told reporters: "My speed wasn't too good on the greens. I was leaving a lot of putts short.
"But I guess that's to be expected. It's the first day competitively with a bit of a new grip. But I felt like it was pretty good."
Shane Lowry also carded an opening, overcoming the inconvenience of a cracked driver - damaged in practice - to make a solid start.
Using a back-up club, his eagle on the 10th gave him a platform for the weekend, but Graeme McDowell has work to do. The Portrush man endured a frustrating round, finishing on two-over as three birdies were undone by three bogeys and a punishing double bogey on the fourth.
Piercy was seven under par after 11 holes but eventually carded a 66 after a bogey on the last when his ball plugged in a grass bank on the edge of a lake, while Fraser also reached seven under before dropping his only shot of the day on the eighth.
It was nevertheless a superb effort from the 37-year-old Australian, who won in Malaysia a fortnight ago and was 15th in the Perth International last week before making the 11,000-mile journey to Miami.
Phil Mickelson, who has not won since claiming his fifth major title in the 2013 Open at Muirfield, was a shot off the lead, with Danny Willett, Jason Dufner, Charley Hoffman and Honda Classic winner Adam Scott all on four under.
"I hit a lot of good shots, I was really pleased with the way the round went," Mickelson told Sky Sports. "I probably let a few shots go early on, but I hit a lot of good shots, I was patient with the round and on my second nine I was able to make some birdies and capitalise on some of the shots."
Spieth carded five birdies and two bogeys to finish three under, with world number two Day faring the worst of the marquee group with a level-par 72.
Asked about playing alongside Day and McIlroy, Spieth told Sky Sports: "We had fun and for a while there were feeding off each other, turning in two, two and three under.
"It was nice to try and get into a rhythm together because the last few weeks have been a little rough on all three of us.
"I've been doing quite a bit of work. I don't feel great about the way I am striking the ball. I'm working really hard trying to develop patience through my swing and get into my right side. I have been transitioning a little quick and that leads to a shorter swing and more inconsistent ball striking."