Players were greeted with perfect weather on Thursday, a year after rain turned TPC Scottsdale into a soggy, wild mess.
Clark was the best of the bunch, opening with a birdie and adding four straight starting on No.8 on a day win in which 24 players shot 68 or better before play was suspended by darkness.
"You can't necessarily control the score and what happens to your golf ball, but you can control your thoughts," Clark said. "So it was a good reminder for me to get back to, hey, when I'm playing my best, I look at the glass more half full than I do half empty."
Lee Hodges had two eagles on the back nine - his front - and added three straight birdies starting at No.1 to shoot 65. He was tied with Taylor Moore, who eagled the par-5 third hole to cap a seven-under stretch in seven holes.
Justin Thomas had six birdies and was among six players who shot 66. Jordan Spieth escaped from some difficult spots to shoot 68 in his second tournament since offseason wrist surgery.
Top-ranked Scottie Scheffler had a wild ride, holing out from a fairway bunker on No.10 in a 69 in his second start since puncturing his hand while making ravioli for Christmas dinner.
Clark got off to a great start, opening with a birdie before rolling in four straight starting at the par-4 eighth. The 2023 US Open champion two-putted for another birdie on the par-5 13th and hit his third shot to tap-in range on the par-5 15th to reach seven under.
Clark was clearly frustrated after pulling his tee shot left into the water at the reachable par-4 17th, but hit a magnificent pitch shot to save par before closing with an easy par on 18.
"Needless to say that's a birdie hole, and to hit it in the water and not really have a birdie look is kind of unfortunate," Clark said. "But to come away with a par was awesome - that was huge."
Starting on the back nine, Thomas took advantage of the benign conditions in the morning wave, overcoming a bogey on the par-3 12th with consecutive birdies on Nos.14-15. He two-putted for birdie on the par-5 third and rolled in a 45-foot birdie on the par-4 fifth after having to hit his approach shot around a tree.
Thomas closed out a three-under 32 on his back nine with a 15-foot birdie on No.9.
Scheffler opened with a bogey, failed to take advantage of the downwind par-3 third and took another bogey when he shanked a bunker shot on the par-4 fifth. Scheffler never seems to stay down for long and set off one of the loudest roars of the first round when he holed out a 104-yard fairway bunker shot for eagle on No.10.
The two-time Phoenix Open champion made a double bogey on the par-3 12th after hitting his tee shot in the water, but birdied the par-5 13th and rolled in seven-foot eagle putt on No.15. He got up and down for birdie from right of the par-4 17th and just missed another on 18.
Min Woo Lee (70) is the only Australian in the field and is six behind.
