The American braved the chilly and gusty conditions around the Memorial Park Golf Course to sign for a two under 68, enough to move to 15 under for the tournament, four shots clear of England's Ben Taylor who's alone in second.
Finau was superlative off the tee, finding every fairway and missing just two greens. Birdies came on the par five eighth and the par four 14th, while he rolled in a nine-footer on the last to save par.
"I hit the driver as good as I've ever hit it," said the world number 15, as per pgatour.com.
"That was a really good round. I think the score doesn't say that, but I think I played better than yesterday. You know, yesterday I shot 62, but today that 68 I thought was pretty impressive for the conditions."
Sunday silverware would mark Finau's third victory in his last seven starts.
"Winning just breeds confidence," he continued.
"I've always felt like I was confident to win, but you've got to do it, you've got to make it happen. Having done that back-to-back [in July], I think it just breeds confidence more into my belief and to my game."
Further down the leaderboard, former US Open champion Justin Rose is tied for third with Americans Wyndham Clark and Tony Alexander on eight under, seven shots off the lead.