|Zozo Championship, round one leaderboard|
|-8 S Munoz (Col); -7 T Hatton (Eng), J Thomas (US)|
|Selected:-5 J Rose (Eng); -4 J Rahm (Spa); -3 P Casey (Eng), M Fitzpatrick (Eng); -2 T Fleetwood (Eng); +1 R McIlroy (NI); +4 T Woods (US)|
Rory McIlroy completed an error-ridden back nine on day one of the Zozo Championship by snapping one of his irons after a poor shot on the 18th.
The Northern Irishman was three under par at the turn but two double bogeys and three bogeys left him nine behind the leader, Colombia's Sebastian Munoz.
One of the double bogeys came at the 18th as he carded a one-over-par 73.
England's Tyrrell Hatton continued his fine run of form as a 65 left him sharing second with Justin Thomas.
Fellow Englishman Justin Rose is on five under and tied for ninth, while his compatriots Paul Casey and Matthew Fitzpatrick are two shots further back on three under.
McIlroy's frustrations boiled over after missing the green with his third shot at the par-four 18th at Sherwood Country Club in California. He pushed his club into the ground until the shaft snapped and then had a couple of practice swings with it as he marched to the green.
The four-time major also endured a torrid back nine in Sunday's final round at the CJ Cup in Las Vegas as he dropped six shots in his final holes to plummet from a likely top-10 finish to a share of 21st spot.
Defending champion Tiger Woods, preparing for his Masters title defence in three weeks, had an even more chastening day in California as a four-over-par 76 left him sharing 75th spot with only Adam Long behind him in the 78-strong field.
Woods, who has five wins and five second place finishes at Sherwood, tied Sam Snead's record for 82 PGA Tour wins by winning this event when it was staged in Japan last year. This year's tournament is being played in the US because of the coronavirus pandemic.