The 20-year-old Bangkokian managed to play 12 holes but was clearly stumbling and unable to play further.
Ariya said she started to feel tightness in her knee during Thursday's second round.
She met with doctors after the round. They taped her knee for the third round Friday night but the pain became more intense and she was forced to withdraw after the 12th hole.
She is “very disappointed” she told the media, “because it’s the Olympics, and I told my caddie, ‘I want to finish four days. I don’t care how many over I’m going to be,’ but I’m thinking about my career.”
The reigning British Women's Open champion had carded three bogeys, two doubles and three triples and was 12 over for the day when she called it quits.
“After the (first) round, I started feeling pain,” she said. “I feel a little bit tight, then in the second round, like almost last three holes, but I finish okay. After that, I rest, and I start to hit the ball after I play yesterday, and then I hurt, so I stop.
“I went to putt and I can’t bend… down, like a sharp pain just happened.”
Ariya was the first-round leader after an opening 6-under 65 and shot even-par 71 on Thursday before coming completely unravelled in Round Three.
The second Thai golfer, Pornanong “Waew” Phatlum, had her best round on Friday, Brazil time. She shot two-under par 69, for a three round score of 212.
Her tournament total of one-under par puts her in 22nd place in the 60-woman field.
Inbee Park of Korea is in first place heading into Saturday’s final round, at 11-under par.
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