Not even that could dampen Na's second round that gave him the lead halfway through the soggy tournament.
Na took the penalty drop near the 17th fairway, and hit a blind approach shot over bleachers to the back side of the 18th green. His two-putt from 20 feet wrapped up a 4-under 66.
"A good bogey," Na said.
At 10-under 130, Na was two strokes ahead of
Na also made some long birdie putts. His 30-footer off the fringe at No. 14 came right after rolling in a 22-footer at the 13th, where he broke into a dance for the rowdy fans surrounding the par 3 situated on the edge of Hogan's Alley.
"I want to call it the Big Bird dance. ... It just came out. I wasn't really thinking about it," the 31-year-old Na said. "You know, the crowd has been very supportive. I felt like I was from Texas."
Spieth finished with a 73, nine strokes worse than his opening round 64 that had him in a four-way tie on top. He dropped seven strokes back at 3 under, in a crowded tie for 15th place.
Tom Lehman holds lead at Senior
Tom Lehman started the second round of the Senior PGA Championship on the 10th tee Friday afternoon. He might as well have started it on a launch pad.
Lehman birdied three of his first four holes on French Lick Resort's rigorous Pete Dye Course and kept right on going. He shot a 5-under 67 — matching the best round of the week — to take the lead at the halfway point of the Champions Tour's second major championship of the year.
At 4 under, Lehman led his playing partner of the first two rounds, defending champion Colin Montgomerie, and Brian Henninger by a stroke. Montgomerie shot 69, and Henninger matched Lehman's 67.
The severity of the course has caused some players to grumble about Dye, its designer. Not Lehman.
"Pete Dye courses, in general, I enjoy," said Lehman, who hit 16 greens in regulation Friday. "I really enjoy his style of architecture. I like the way he thinks. I like the way he makes the player think."
There have been only seven rounds in the 60s, all of which came with milder weather conditions prevailing Friday, when tournament officials trimmed more than 100 yards off the first-round setup, from 7,040 yards to 6,914.