|WGC-Cadillac Championship first round leaderboard:|
|-6: S Piercy (US), M Fraser (Aus); -5: P Mickelson (US); -4: D Willett (Eng), A Scott (Aus), J Dufner (US), C Hoffman (US); -3 J Spieth (US), J Walker (US), B Watson (US); Selected others:-2 J Donaldson (Wal), R Fowler (US), A Sullivan (Eng); -1 R McIlroy (NI), S Lowry (Ire), P Casey (Eng)|
Rory McIlroy refused to blame a change of putting technique after finishing day one of the first World Golf Championship of the season five shots off the pace.
McIlroy, 26, finished the first round of the WGC-Cadillac with a one-under par 71 using his new cross-handed grip.
Scott Piercy of the United States and Australia's Marcus Fraser share the lead after hitting 66 at Trump Doral.
"I was leaving a lot of putts short but that's to be expected," said McIlroy.
"It's the first day competitively with a bit of a new grip. But I felt like it was pretty good."
The Northern Ireland player changed his putting method after missing the cut at last week's Honda Classic and is now putting with his left hand below the right on the grip.
World number one Jordan Spieth, who played alongside McIlroy and US PGA champion Jason Day, is three shots behind the leaders.
"I'm very pleased to get in under par on this golf course," said 22-year-old American Spieth, who carded five birdies and two bogeys.
"This course normally gets my number but I beat it today."