Tentative Rory McIlroy still searching for answers to his puzzling form

World number one has begun the defence of the Honda Classic title at Palm Beach

Rory McIlroy's slow start to the new season continued as he began the defence of his Honda Classic title at Palm Beach.

The world No 1 was level par for his first round, placing him six shots behind leader Camilo Villegas.

McIlroy has struggled to rediscover the form that has elevated his to the top of the world rankings so far this year – after moving to new sponsor Nike – highlighted by his first-round exit at the Match Play Championship to countryman Shane Lowry last week.

"It's hard to commit to the shot that you need to play every time," McIlroy said. "I felt like I hit the ball okay, not as good as I can, but it's getting there."

The 23-year-old was steady as he remained level with the card through his first five holes but dropped a stroke at the par-four sixth. He recovered the shot at the ninth before beginning his run home in near-perfect conditions in south Florida. It was more of the same on the back nine as he picked up a shot on the 14th but bogeyed the last.

It was a very different story for 2010 champion Villegas, who eagled the 18th to finish off a blemish-free round. It was quite a charge from the Colombian, who was one under through 12, then picked up five strokes over the lost six holes. "It's a tough golf course," said Villegas. "And I like tough golf courses."

Behind him was a group of four players on five under – Branden Grace, Graham DeLaet, Rickie Fowler and Robert Streb. A group of 10 players was a stroke further back including England's world No 9 Lee Westwood and Americans Boo Weekley and Dustin Johnson.

Tiger Woods, who was runner-up to McIlroy last year, had to settle for an even round of 70 just like the Ulsterman after battling back from bogeys at the 10th, his opener, and 13th. The 14-time major winner and current World No 2 took until the par-five third to card his first birdie, sinking a six-footer, before he somehow escaped with par at the sixth after hooking his drive left and having to play out of a marsh.

"It was only half-submerged so I could play some sort of explosion shot and get it back in the fairway," said Woods, who used a nine-iron out of the water. "I wasn't trying to advance it very far, just get it back on the fairway."