Two-time FedEx Cup winner Rory McIlroy fell eight strokes off the pace as Si Woo Kim shot an 8-under 62 to grab a share of the lead with JJ Spaun.
South Korean Kim admitted he was "excited" to produce a "perfect" shot after bogeying the par-four 18th from 167 yards to complete a strong 6-under finish on his last six holes,
"I just tried, like, (see) 10 feet to the left and it was (a) perfect shot, (it went out)," he told reporters.
"Yeah, I was excited," he added.
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His American co-leader, meanwhile, carded eight birdies at TPC
"I think I putted really well and I drove it really well. I think I hit 15 out of 18 greens, so that's a pretty good combo. When you hit a lot of greens,
Severoir McIlroy shot an even-par 70, along with Scot Russell Knox, eight strokes off the pace.
The top 125 players in the regular season point standings (120 play) qualified and only the top 70 after this week
The top 70 after this week advance to the second round, the BMW Championship.