Rory McIlroy kept his promise to "grind it out" when the going got tough to post a first round of 73 in the £5.8million WGC-Cadillac Championship in Miami today.

McIlroy was three over par with three holes of the Blue Monster course at Doral to play, but birdied two of them to finish seven shots behind playing partner Tiger Woods, who shared the lead with Sergio Garcia, Graeme McDowell, US Masters champion Bubba Watson and Sweden's Fredrik Jacobson.

"It was nice to sneak in a couple of birdies in the last three holes and make it look somewhat respectable" - Rory McIlroy

World number one McIlroy is now an approximate 18 over par for 98 completed holes in 2013, but it could have been worse but for a superb eagle at the par-five first hole, his 10th, with the swing problem he worked so hard on over the weekend clearly still an issue.

In contrast, Woods carded nine birdies in his 66 as the 65-strong field took advantage of calm conditions, with Peter Hanson and Phil Mickelson among those one off the lead and the likes of Ian Poulter and defending champion Justin Rose a stroke further back on four under.

McIlroy, making his first appearance since his controversial withdrawal from the Honda Classic last week, told Sky Sports 3: "It was a bit of a struggle to be honest.

"I hit some good shots, I hit some not-so good shots. As I have been saying all week this is a work in progress, I am staying patient and I have another three rounds to work on it more and shoot a few good scores.

"I just had to play each hole as it came and shoot the best score possible. It was nice to sneak in a couple of birdies in the last three holes and make it look somewhat respectable, even though everyone seems to be going pretty low out there; it was a day where it was perfect scoring conditions.

"I wasn't putting as much pressure on myself and that's why I didn't get as frustrated. If I had played like that last week I would have been not so happy but I understand it's a work in progress and hopefully it will come together soon."

Woods, who revealed he had been working on his putting under the guidance of Ryder Cup team-mate Steve Stricker - who shot 67 - added: "I don't think we're going to get all four days in this wind, it's gotta switch sometime and come from the east and if it does then the course plays more difficult. But today was as easy as it gets round this place."

"Today was as easy as it gets round this place" - Tiger Woods

McIlroy has dominated the golfing headlines this year, firstly for signing a multi-million pound deal with Nike and then missing the cut in his first event with his new equipment in Abu Dhabi.

He then lost to Shane Lowry in the first round of the WGC Accenture Match Play, before things went from bad to worse as he quit the defence of his Honda Classic title last week after completing just eight holes of his second round.

McIlroy issued a full apology for his withdrawal yesterday, admitting the pain from a wisdom tooth and being in a "bad place mentally" was no excuse for walking off the course after playing those eight holes in seven over par.

The 23-year-old spent all weekend working with coach Michael Bannon to iron out a flaw in his backswing, but admitted getting the club in the right position still felt "very alien" to him.

Starting on the back nine today, McIlroy twice found sand on the 551-yard par-five 10th, but saved par and repeated the trick on the 11th and 12th before a wayward tee-shot on the par-three 13th resulted in a bogey.

Another bogey followed on the 14th before a first birdie of the day from nine feet on the 15th, but another dropped shot on the 18th took the Northern Irishman to the turn in 38.

Having promised to "grind it out" better when the going gets tough, McIlroy looked to have got his reward when he responded to another missed fairway on the par-five first by hitting a superb iron shot through the trees to the back edge of the green and holing from 18ft for an eagle three.

However, that was instantly followed by a hat-trick of bogeys - two of them down to three-putting - and it took birdies on the seventh and eighth to rescue a respectable total.

Luke Donald, playing alongside Woods and McIlroy, returned a 70 despite two sixes on his card, while Lee Westwood and Ernie Els matched McIlroy's 73.

Ryder Cup team-mates Francesco Molinari and Paul Lawrie shared last place on six over.