DUBLIN, Ohio, May 30 (Reuters) - While Rory McIlroy suffered a nightmare start, South African Charl Schwartzel regained welcome form with his putter to charge into an early one-shot lead in Thursday's opening round at the Memorial Tournament.
Former Masters champion Schwartzel changed his putting grip after just four holes at a sun-drenched Muirfield Village Golf Club, the move reaping instant reward as he went on to fire a sizzling seven-under-par 65.
American Scott Piercy mixed eight birdies with two bogeys to card a 66 but world number two McIlroy, seeking his first victory of the year, battled to a 78 that included a four-putt for an ugly double-bogey at the par-three 12th.
Top-ranked Tiger Woods, the reigning champion and a five-times winner of the elite PGA Tour event hosted by Jack Nicklaus, was among the late starters on a muggy afternoon at Muirfield Village where the winds began to strengthen.
Schwartzel, who missed the cut at last week's Crowne Plaza Invitational, was delighted to regain form on the greens as he piled up 10 birdies, one bogey and a surprising double-bogey at the par-three eighth to take early control.
"The birdie on the last definitely will make my evening a lot better," the 28-year-old South African told reporters after ending his round by sinking a curling 12-footer to birdie the par-four ninth.
"I felt like I played really well, sort of ticking the ball over and got it to eight under," he said of his position with two holes remaining before he sliced his tee shot into the right greenside bunker at the eighth.
"Just had a bad one on No. 8, made a double. And that was the very worst I played all day. Today was one of those rounds where I really did flush it.
Schwartzel decided to change his putting grip after three-putting from just six feet to bogey the par-four 13th, and he promptly birdied the next four holes.
"I flushed it for the first four holes and two-putted for birdie on 11," he said. "And hit it close on 13, looked like I was going to go two under and I made bogey.
"But I went to the next hole, changed the grip and they (the putts) started pouring in. So it worked."
Asked what had most pleased him about his round, Schwartzel replied: "Probably my mental game. I hit the ball well off the tee, but I had a couple of three putts on the front nine.
"But I stayed positive and didn't beat myself up, and that allowed me to have a good back nine."
While Schwartzel revelled in the hot, breezy conditions on a perfectly manicured Muirfield Village layout, McIlroy huffed and puffed as he plummeted toward the bottom of the leaderboard after repeatedly leaking shots to the right.
"That's sort of been my big miss all of this year is leaving that shot out to the right," McIlroy said after a round that included two birdies, six bogeys and his costly double at the 12th.
"It cost me today, obviously. I hit a few shots, especially around the front nine, in the water and stuff. Yeah, it was just a bit of a struggle out there.
"The game just isn't all there at the minute, but I'm working hard and I'm trying to figure things out. Hopefully they'll come around soon."
McIlroy, whose best finish on the 2013 PGA Tour was a runner-up spot at last month's Texas Open, missed the cut at last year's Memorial Tournament and knows what he needs to do in Friday's second round if he is to avoid a repeat.
"I'll head to the range and practise most of the afternoon," said the 24-year-old Northern Irishman, a six-times winner on the U.S. circuit who already has two major victories to his name.
"I need to shoot something like 66 or 65 to probably make the weekend. That will be the target tomorrow, try to shoot the lowest score possible and see what happens." (Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)