Lexi Thompson received a four-stroke penalty with six holes to play in the final round of the first women’s major of the year for making an incorrect ball placement one day earlier.

Lexi Thompson's trial by TV viewer shows why golf struggles to grow | Anya Alvarez Read more

The extraordinary delayed penalty knocked the American golfer out of the lead at the ANA Inspiration tournament in Rancho Mirage, California.

After gathering her composure when her three-shot lead vanished, the 22-year-old rallied to card a closing five-under 67 and tie at 14-under 274 with South Korea’s So Yeon Ryu, who had a 68. But Ryu triumphed with a birdie at the first extra hole.

Thompson was penalised 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 on Saturday.

The LPGA did not decide on a penalty until Sunday, when Thompson had a three-stroke lead and appeared to be cruising to her second major championship. The organisation confirmed the video review was prompted by an email from a television viewer in a statement issued on Sunday evening. Thompson was penalised 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 birdied the par-4 13th hole. Inbee Park birdied the 16th hole moments later to create a five-person tie for the lead. Meanwhile, course officials laboriously changed every number next to Thompson’s name on the scoreboard.

“It’s unfortunate what happened,” Thompson said afterwards. “I did not mean that at all. I didn’t realise I did that. I fought strong through the finish and it was great to see the fans behind me. I played amazing today, probably the best golf I played all week. Wasn’t expecting that on whatever hole that was. I did not intentionally do that. So to the officials, or whoever called in, that was not my purpose. I didn’t even realise I did that.”

Facebook Twitter Pinterest Lexi Thompson reacts following her loss in the play-off. Photograph: Gary A Vasquez/USA Today Sports

LPGA rules official Sue Witters said later the email was sent through the LPGA.com Fan Feedback portal and received by the tour’s website team. “I’m 100% sure it was not intentional,” Witters said. “It was a hard thing to do. To be honest, it made me sick.”

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 defence on Twitter.

Tiger Woods (@TigerWoods) Viewers at home should not be officials wearing stripes. Let's go @Lexi, win this thing anyway.

Others joined Woods’ dismay at the stunning turn of events.

Cheyenne Woods (@Cheyenne_Woods) Viewers should not be able to call in rulings.

Alison Walshe (@Walsheyyy) Infuriated w @Lexi ruling. Who intentionally seeks an inch on a tap in. TV viewers need a day job or have no effect on our system.

Brittany Lincicome (@Brittany1golf) Come on @Lexi you can do it!!!!!

We really need to do something about people being able to call in. Especially days later 😥😡. Poor girl