That Jutanugarn steadied herself to emerge victorious from a sudden death play-off with Kim Hyo-joo points towards formidable mental strength.
Jutanugarn wound up at 1-over 73, leaving her at 11-under 277 for 72 holes.
She made seven pars in a row before back-to-back bogeys on No. 8 and 9 dropped her one shot behind Jutanugarn.
The pair then needed four extra holes to be separated, with a par on the 18th hole enough for Jutanugarn to win the championship.
South Korea's Kim Hyo-joo was alone in third after shooting a four-under 68 while another shot behind was Kim Ji-hyun (70) at five-under 211. Smith, who is seeking her first LPGA career title, had the luxury of sleeping in Saturday morning because she finished her second round on Friday. She made putt after putt to put pressure on Jutanugarn, including a stunning 50-footer on 15 that pulled her within one shot of the lead. Many players are yet to complete their final round.
She has a way to go, but nonetheless took delight at seeing her name atop the leaderboard the entire round.
"I could see she was getting in that mode where she was starting to think about what could happen", Luark said.More news: Supreme Court refuses to stay release of Rajinikanth-starrer ‘Kaala’
Woods wasn't alone in missing short putts. So we had a really good lesson before Kingsmill and then I actually missed the cut in Kingsmill, but felt like I played really well. Back-to-back bogeys to close from the Thai, for an 11 under par aggregate, conceded the two-stroke lead restored at the 16th and meant the play-off which all onlookers, in reality, expected her to lose.
"I want to play golf as long as I can [and] just try to win my next tournament" she told CNN.
It took four holes more than she would have wanted, but Jutanugarn was still able to celebrate her victory with sister Moriya, who finished in 41st. I'm really confident with my bunker shot right now.
Smith, who has not won in 222 LPGA tournaments, carded a second consecutive 67 on Friday, but she shot two bogeys in a third-round 74.
"I've kind of been playing a little bit better since San Francisco so it's just been like gradually a little bit getting better", said Oh who finished 4th at her last start in MI. We send videos and that, but there's something about in person that he seems to get a pretty good gist of what's going on even on the golf course.
Michelle Wie is among eight players tied for fourth, seven shots off the lead.
She did well to hole from eight feet to salvage a bogey and then stripe a confident long-iron down the centre of the fairway at the last just as Kim nailed a tricky six-footer for par to cap a bogey-free 67.