Rory McIlroy and Justin Rose both started the Honda Classic in Florida yesterday with four-under-ar rounds of 66 – but Ian Poulter pulled out ill before the start.
Needing to win to topple the resting Luke Donald as world No 1, McIlroy set the early clubhouse lead, although out on the course Americans Davis Love and Dicky Pride were both five under.
Rose joined the Northern Irishman after hitting back from an early double bogey with an eagle and four birdies.
Poulter, laid low by pneumonia, was due to play with Tiger Woods and Lee Westwood, but said on Twitter: “Sorry guys – never been so disappointed in pulling out of a tournament. Never felt so rough.”
His place went to Argentina’s Miguel Angel Carballo, a PGA Tour rookie ranked 299th in the world.
McIlroy grabbed his first birdie after a 165-yard approach to five feet on the 14th – his fifth – and added a 12-foot putt on the short 17th before two-putting the 556-yard 18th to turn in 32.
Further birdies came on the second and seventh, but he was more than 50 feet from the flag on the next green and three-putted to drop his only stroke.
Rose’s double bogey came at the second, but he eagled the next from nine feet, then had a hat-trick of birdies from the fifth and picked up another at the 16th.
Ryder Cup captain Love, who insists he will play against Europe in Chicago in September if he qualifies, holed-in-one with a five-iron to the 217-yard fifth and with three successive birdies from the seventh turned in 31.
The 47-year-old bogeyed the 10th, but birdied the 17th to be alongside Pride, who still had two holes to play.
McIlroy said: “It’s a solid opening round. I felt like the course was very scorable – it’s obviously very soft after the rain.
“I only made that one mistake on the eighth green with a three-putt. Apart from that I was very happy with how the day went.
“I feel like I’ve got a few targets in my head and I’m sort of striving to get to those.
“Obviously with all of the talk of No 1 it would be great to get to that position at some point.
“I feel like I’m playing good enough to challenge for it at least, but I’m working towards trying to peak my game from April through to August for the four majors and for the big tournaments.”