RANCHO MIRAGE, Calif. (AP) Lexi Thompson received a four-stroke penalty with six holes to play in the final round of the ANA Inspiration on Sunday for making an incorrect ball placement one day earlier.
The extraordinary delayed penalty knocked Thompson out of the lead at the LPGA Tour's first major of the year.
After gathering her composure when her three-shot lead vanished, the 22-year-old responded with a birdie on the 13th hole to pull even with So Yeon Ryu, Minjee Lee and Suzann Pettersen atop the new leaderboard.
Thompson was penalized after a television viewer apparently alerted officials that Thompson has marked her ball and then put it back in an improper place before a 1-foot putt on the 17th green in the third round Saturday.
The LPGA incredibly didn't decide on a penalty until Sunday, when Thompson had a three-stroke lead and appeared to be cruising to her second major championship.
Thompson was penalized two strokes for an incorrect ball placement and two strokes for an incorrect scorecard.
Thompson reacted with disbelief when officials told her of the decision while she walked to the 13th tee.
''Is this a joke?'' Thompson asked.
After being assured it wasn't, she responded: ''This is ridiculous.''
Thompson appeared to choke up slightly, but gathered herself and mashed a drive, eventually posting a birdie on the par-4 13th hole.
Inbee Park birdied the 16th hole moments later to create a five-person tie for the lead. Meanwhile, Dinah Shore Course officials laboriously changed every number next to Thompson's name on the scoreboard across from Poppie's Pond at the Dinah Shore Course.
Thompson won this tournament in 2014, and she has excelled for four consecutive years at the LPGA's first major of the season.
Golf fans on the course and the Internet erupted with outrage when the LPGA's decision became understood. Tiger Woods immediately came to Thompson's defense on Twitter.
''Viewers at home should not be officials wearing stripes,'' Woods wrote. ''Let's go (at)Lexi, win this thing anyway.''