The 56-year-old Triplett forced the playoff with a similar left-to-right breaker for birdie on the par-5 18th, then matched Austin with a par on their first extra trip down the tree-lined hole.
"It was the exact same putt I had the first time through,'' Triplett said.
Playing together, Triplett and Austin each shot 3-under 68 to finish at 10-under 203 at Newport Beach Country Club.
"We had our chances and neither one of us could get a stranglehold on it,'' Triplett said. "I feel pretty lucky to have just had a chance to be in the playoff.''
Austin parred the 18th in regulation, then drove into the right rough on both extra holes. He left a greenside bunker shot well short on the first playoff hole, and hit his approach to the right of the green on the second.
"He hit three quality shots there to win, but I gave him a chance to win,'' Austin said. "He should have never even had a chance. That's how it goes. I didn't get the job done when I was supposed to.''
Triplett did on the eagle try.
"Got a couple tries at it,'' Triplett said. "We both hit great shots in regulation. They just hit that kikuyu edge there. Very easily Woody's ball could have kicked up there 3 feet from the hole for eagle. I was fortunate to make a putt and get in the playoff.''
Jeff Maggert and Scott McCarron finished a stroke out of the playoff. McCarron three-putted the 18th from 30 feet for par and a 68. Maggert shot 65, but couldn't overcome a four-putt triple bogey on 18 in the first round Friday.
"It's a tough game,'' Quinn said. "Right now I'm burning inside thinking I should have done a lot more than that. ... I didn't miss a shot for two days and played just flawless golf, and today I looked like about an 8 handicap, or I felt like it.''
Newport Beach resident Fred Couples closed with a 69 to tie for 10th at 6 under.