"So, yeah, I had fun. What did I shoot? 6-under to finish the tournament on any given week is solid. Just the other girls played better than me."
There are four tournaments remaining before the season-ending CME Group Tour Championship.
With the result, Ko jumped ahead of Aussie Minjee Lee and Brooke Henderson of Canada to sit first on the LPGA's season standings.
Hull's victory was her first on the LPGA Tour in nearly six years and she loved the theatre of the final hour at Old American Golf Club as much as soaking herself with champagne when she held one for the one-shot victory.
"I found it exciting," Hull said. "When Janet made eagle on 17, I enjoyed that. It made me want to birdie the last. It was great fun."
Janet is the nickname for Xiyu Lin of China, and she roared into the mix with a 12-foot birdie putt on the par-3 16th and then a 35-foot eagle putt at the par-5 17th. That gave Lin a share of the lead, but only momentarily.
Hull hit a lob wedge from 78 yards to 4 feet on the 17th and made that for her final birdie, taking a one-shot lead to the final hole.
The pin on the 18th was all the way back, with a huge slope just left of the green. Hull went at the flag, tugged it a little and watched it stay on the collar left of the flag. Lin, who closed with a 65, put her approach on the green, just inside Hull's.
Lin's birdie putt to force a playoff lost speed and missed just to the left. It was her third runner-up finish this year, and second in the last month. She wiped away tears when it was over.
"It's funny, my coach and I had a joke, trying to see how high of a world ranking I can get without a win. I mean, it's not fun, but it's fun," Lin said. "Any other week, I mean there is 140 players out there and I came up second. It sucks, but at the other side, it's good."
Ko also was in the mix and was tied for the lead until missing a couple of birdie chances from inside 10 feet.
Atthaya Thitikul, the 19-year-old from Thailand who won last week in Arkansas, needed a win to reach No. 1 in the women's world ranking. Instead, she shot 67 and finished alone in fourth, moving to No. 2 ahead of Nelly Korda.
- with AP