Jordan Spieth has no idea what it is like to play from behind at the Travelers Championship.
The defending champion led after every round last year in his first visit to TPC River Highlands, and a shot a 7-under 63 on Thursday to match Zach Johnson for the first-round lead.
Spieth had six birdies and an eagle out the bunker on par-5 sixth hole -- a shot reminiscent of the greenside bunker shot that gave him a victory last year over Daniel Berger in a playoff.
Johnson went out in the morning and led for most of the day. He had eight birdies, including six straight on the back nine, one off than the course record.
Rory McIlroy missed a 13-foot putt for par on the final hole that would have given him a share of the lead and finished in a three-way tie for third place with Brian Harmon and Peter Malnati.
Brooks Koepka followed his second straight U.S. Open victory with a 68.