Finau made a 31-foot putt for birdie on the 15th green to strengthen his grip on the lead, as the 6-foot-4 Utah player calmly and confidently walked the TPC Twin Cities course in his white hat and aqua-striped polo.
Piercy followed his tournament-record 54-hole score with a wince-inducing 76 to tie for fourth, four strokes back.
Finau finished at 17-under 267. Sungjae Im (68) and Emiliano Grillo (71) tied for second place. James Hahn surged up the board with a 65 to match Piercy and Tom Hoge (70) at 13 under.
Piercy bogeyed four of six holes before a triple-bogey implosion on No. 14, allowing Finau — playing in the preceding trio — to take over for good on his way to his third career tour victory.
Finau made a 31-foot putt for birdie on the 15th green to strengthen his grip on the lead, as the 6-foot-4 Utah player calmly and confidently walked the TPC Twin Cities course in his white hat and aqua-striped polo.