Thompson's round was one stroke better than the mark first posted in 2003 by Tom Kite and Joe Inman, and then equaled by Bob Gilder in 2004 and Jay Haas in 2006, on the Jack Nicklaus-designed layout at Hills Country Club.
Kuramoto was tied for the lead as he played the par-5 18th hole, one of the easiest on the course, but he suffered a double bogey.
Thompson's effort came as a surprise since his best finish this season has been a tie for 36th. He has won three times on the Champions Tour, the last of the victories coming six years ago.
"It was one of those rounds where everything went where I was looking," Thompson said. "I hit the ball solid in the last two starts, but today everything seemed to come together."