Rudy Caparas of Lynnwood and Tanner Kovacevich of Puyallup are two shots back.
Defending champion Brian Humphreys of Camas shot a 77, which is tied for 19th and the top score among Clark County golfers.
Yi used his practice round Tuesday to craft a conservative strategy for the Camas course.
“I learned how to strategize on various holes, when to be aggressive and when to lay back a little,” Yi said. “You have to be really cautious with your drives. There’s a lot of hazards out there. You don’t want to put yourself in too much trouble.”
Yi did not get flustered after bogeying the first hole. He sunk a 10-foot par putt on No. 2, then birdied Nos. 5 and 6 to move to 1-under.
After finishing the front nine in 1-under 35, Yi birdied 11 and 14 to move to 3-under. He bogeyed 15, but got that stroke back with a birdie on the final hole.
In the 80-golfer field, the higher seeds teed off earliest Wednesday. Yi was seeded almost exactly in the middle of the field.
“I just have to go out there tomorrow, stick to the game plan and not put too much pressure on myself,” he said.
Humphreys was not able to avoid trouble early in his round, recording a double bogey, bogey and another double bogey in his first three holes.
The sophomore settled down in the middle of the round, but had a triple bogey on the 15th hole and a bogey on the 18th.
“I was hitting it good and giving myself birdie opportunities,” Humphreys said. “But I wasn’t making enough putts to keep up with all the doubles and triples I was making.”
Kuna hit 16 greens in regulation on the way to his round of 70. The Snohomish sophomore was more aggressive than Yi, playing as if he were in danger of missing the cut.
“I always like to count on the cut being really low, so I played for that,” said Kuna, who finished 18th at state last year.
Caparas, tied for third after shooting 71, had birdies on three of his final four holes. Being near the lead will not be strange for the Lynnwood senior, who was tied for first after last year’s opening round before finishing eighth.
Caparas has adopted a technique to keep his nerves in check — he plays golf three steps and one breath at a time.
“You take three steps and then forget about your last shot,” Caparas said. “Take three steps, then breathe. I take deep breaths. They may be loud, but it calms me down.”
