Harrington matched his lowest score of the year on the PGA Tour Champions, and it was his best opening round of the season on the 50-and-older circuit. The 50-year-old Irishman is second in the Charles Schwab Cup standings, though still well behind Steven Alker.
Harrington already has won once this year at the U.S. Senior Open. He has not been outside the top seven on the leaderboard over his past eight rounds.
Triplett stated on the back nine at Canyon Meadows and was 3 under through two holes after his birdie-eagle start.
He was a runner-up at the Shaw Charity Classic four years ago.