A birdie on the 18th hole saw Patrick Reed finish the first day of the Hero World Challenge in the Bahamas top of the leaderboard alongside fellow American Patrick Cantlay.
Reed had started strong with birdies on the first two holes but a bogey on the par-three eighth set him back before he carded four birdies on the back nine to sign for a 65.
Cantlay had used a late charge to set the clubhouse lead, with birdies on five of the last six holes in a blemish-free round.
That left the pair three shots clear of Henrik Stenson and Dustin Johnson who were in a tie for third.
Host Tiger Woods struggled as he recorded a first round of 73.
Birdies on the sixth and seventh holes cancelled out bogeys on the second and fifth, but it all went wrong on the par-three 12th as he missed the fairway and then got caught in a water hazard on his way to a triple-bogey.
Collated first round scores in the USPGA Tour Hero World Challenge (USA unless stated, par 72):
65 Patrick Cantlay, Patrick Reed
68 Dustin Johnson, Henrik Stenson (Swe)
69 Alex Noren (Swe), Bubba Watson
70 Justin Thomas, Justin Rose (Eng), Bryson DeChambeau
71 Jason Day (Aus), Keegan Bradley, Jon Rahm (Spa)
72 Tony Finau, Gary Woodland, Rickie Fowler
73 Tiger Woods, Xander Schauffele
74 Hideki Matsuyama (Jpn)
