The first women’s major of the calendar year is due to get underway tomorrow at the Mission Hills Country Club in California.

South Korea’s Ryu So-yeon returns to defend the title she won controversially in 2017 after defeating American Thompson via a play-off.

Thompson led the Ladies Professional Golf Association event by two strokes on the 12th hole during the final round.

However, competition organisers were notified by someone watching on television that on the previous day she had put her ball marker on the 17th green in a different spot to the original placing.

This forced a two-stroke penalty with an additional two shots then deducted for returning an incorrect scorecard.

Thompson, who was left in tears after being told of the penalty with six holes to play, was able to force a play-off against Ryu but eventually lost.

"That night was extremely rough," the 23-year-old was reported as saying by BBC Sport prior to this year’s event.

"I was screaming, crying.

"I had nightmares about it and I still occasionally do."

Thompson added: "It's been rough.

"I stayed off social media after that because media was blowing it up and making me feel terrible.

"I had to let it go and let time pass."

The R&A and United States Golf Association subsequently announced changes to the sport's rules in a bid to reduce the impact of video technology. 

The changes aim to protect players from being penalised for infractions that "could not reasonably have been seen with the naked eye".

They state that a player's reasonable judgement will be accepted, even if later proved wrong by video evidence.

Players are also no longer penalised for returning an incorrect scorecard if they were not aware the scorecard was wrong.

"I'm just happy the rule changed so nobody else can be put through what I was put through last year," Thompson added.

South Korea’s Inbee Park, who won the Founders Cup in Phoenix, Arizona earlier this month, is expected to be among Thompson’s biggest challengers.

Also likely to be in contention is South Korea’s Ko Jin-young, who leads the Race to the CME Globe standings, as well as the United States’ Michelle Wie and Jessica Korda, and Thailand’s Ariya Jutanugarn.