In the high-stakes world of casino gambling, where fortunes are won and lost in the blink of an eye, one woman managed to turn the tables on some of the world's most prestigious casinos. Her name is Cheung Yin "Kelly" Sun, and her story reads like a Hollywood thriller—complete with millions of dollars, international intrigue, courtroom battles, and a technique so controversial it sparked a global debate about the line between genius and cheating.

Kelly Sun's story begins in Northern China, where she was born into what should have been a life of privilege. Her father's family had made fortunes in banking, but China's Cultural Revolution under Mao Zedong turned their world upside down. The wealthy were imprisoned, their belongings confiscated, and Kelly's father was sent to a work camp during the final years of Mao's reign.

"Until I turned seven, I was very poor," Kelly revealed in a rare interview with Cigar Aficionado. "You know how I like shoes now? When I was a little girl, I had no shoes. We were so poor that my mother had to make shoes for us. She cut out pieces of cardboard from cartons, and those were our shoes. My feet got very cold in winter."

After Mao's death, Kelly's father was released and rebuilt his wealth through a wooden products factory. "He got rich again; he got very rich," Kelly says. Suddenly, the girl who wore cardboard shoes was sent to prestigious schools in Shanghai and Hong Kong, developing a taste for the finer things in life—and for gambling.

By age 15, Kelly was already playing high-stakes Chinese poker with a fake ID, sneaking onto gambling cruises from Hong Kong and making her way to Macau casinos while still underage. Her seminal gambling experience came when she turned AU$2,200 into AU$220,000 playing baccarat. She bought herself a Rolex with her winnings—then gave it away to someone who complimented it, perhaps establishing the philosophy of easy-come, easy-go that would define her early gambling career.

Throughout her 20s, Kelly was the dream casino patron—a high-rolling jet-setter who hemorrhaged millions at casinos worldwide. She played everything: blackjack, baccarat, slots, video poker, craps, and even Texas hold'em. Casino bosses loved her, showering her with penthouse suites, bottles of Champagne, comped dinners, and shopping money. "I lost AU$4.4 million at Palms and stayed in a suite with a pool looking out on the Strip," she remembers.

But everything changed in 2006 at Wynn Las Vegas. Down to her last AU$5,800 from a AU$290,000 bankroll, Kelly encountered a man working the slot machines with remarkable speed. His name was Steven Black, a professional advantage player who specialised in finding casino weaknesses. What started as a simple request for slot machine lessons became an apprenticeship that would transform Kelly from a losing gambler into one of the most feared advantage players in the world.

Black taught Kelly about rebates, blackjack techniques like ace sequencing and shuffle tracking, and most importantly, edge sorting—a technique that would eventually make her tens of millions of dollars and land her in courtrooms around the globe.

Edge sorting is a form of advantage play that exploits manufacturing imperfections in playing cards. Here's how it works: Many playing cards, particularly those made by manufacturers like Gemaco, have slightly asymmetrical patterns on their backs. The decorative design might be cut unevenly by fractions of a millimetre, with one long edge showing more white space or a different pattern orientation than the opposite edge.

In mini-baccarat—where players don't touch the cards and the dealer handles everything—Kelly developed an ingenious social engineering approach. Speaking in Mandarin to Chinese-speaking dealers, she would ask them to rotate certain high-value cards (sixes, sevens, eights, and nines) "for good luck" or due to "superstition." The dealers, eager to please high-betting customers and not understanding the mathematical implications, complied.

Over several shoes (decks), Kelly would systematically get key cards turned 180 degrees from the others. Once the deck was properly "sorted," she could identify these crucial cards from their backs alone. Knowing whether the next card would be high or low gave her an enormous mathematical advantage—turning a game where the house normally holds a 1-2% edge into one where she held perhaps a 6-7% advantage over the casino.

As one court document later explained, this technique exploited "manufacturing defects" where "the pattern on one of the long edges is slightly different from the pattern on the opposite edge."

The pivotal moment came in January 2012 at the Aussie Millions poker tournament in Melbourne, Australia. Poker legend Phil Ivey had just won the AU$290,000 buy-in high-roller event and reportedly had around AU$8.7 million on him. Steven Black saw an opportunity and arranged for Kelly to meet Ivey in Australia.

The partnership got off to a rocky start when Black and Ivey lost AU$4.4 million playing craps using Black's supposed dice control technique. With only half his bankroll remaining and deeply upset, Ivey was sceptical. Kelly stepped in, asking for one night to study the casino's cards. Working through the night, she devised a technique for reading the specific cards being used at the Melbourne casino.

"In one hour, we won the money back plus AU$4.4 million," Kelly recalls. The casino gave the winnings to Phil, who was suddenly a believer. Kelly, Ivey, and Black embarked on a global casino rampage that would generate over AU$44 million in winnings.

From Melbourne, the team hit casinos worldwide: Montreal, Singapore, Macau, and Monte Carlo. Kelly played the role of elegant, designer-clad high roller she had once been—but now with mathematical precision behind every bet. The routine was systematic: arrive at a casino, relax for a day, hit the nightclub, then spend two or three days at the baccarat tables.

Some of their most audacious wins included:

Kelly's teammates called her the "Baccarat Machine" for her tireless focus and emotional detachment. "They didn't want me eating or sleeping. They only wanted me playing," she says. "One time, we played for 24 hours. Phil slept on the floor."

The London win at Crockfords proved to be their undoing. Kelly suggested stopping at AU$7.2 million, fearing pushback, but Ivey wanted to continue. When they finished, Crockfords initially appeared to approve a wire transfer for their AU$15.9 million in winnings. Ivey flew back to Las Vegas to deal with a family emergency, expecting the money to arrive shortly.

It never did.

Crockfords refused to pay, claiming the duo had won by "deceptive means." This triggered a legal battle that would ultimately reach the UK Supreme Court. In October 2017, the highest court in the United Kingdom ruled against Ivey and Sun, determining that while they hadn't cheated in the traditional sense—they didn't mark cards or use devices—they had not "played by the rules" and therefore weren't entitled to the winnings.

Meanwhile, Borgata in Atlantic City filed a lawsuit seeking to recover the AU$13.9 million (plus comps and expected casino profits, totalling AU$22.5 million). In October 2016, U.S. District Court Judge Noel Hillman dismissed fraud claims but ruled that Ivey and Sun had breached their contract with the casino. The judge wrote that they "did not play by the rules" and that edge sorting gave them an unfair advantage that went "beyond the expectation of the game."

After years of appeals, Ivey and Borgata reached an out-of-court settlement in 2020, with terms undisclosed but likely requiring some level of repayment.

Kelly Sun's case ignited fierce debate in gambling circles: Is edge sorting brilliant advantage play or outright cheating?

Arguments for "Genius Advantage Play":

Arguments for "Cheating":

According to research published in The Mathematics of Baccarat Edge Sorting, the technique gave players approximately a 6.765% edge over the house when executed perfectly—an astronomical advantage in casino gambling.

Interestingly, Australian gambling authorities and casinos have taken note. Crown Melbourne and other major Australian venues have implemented countermeasures, including:

Today, Kelly Sun is effectively banned from most major Las Vegas casinos—MGM, Wynn, Caesars—though she can still play at smaller downtown venues. She's turned down consulting offers from casinos wanting to protect themselves against her techniques. Instead, she focuses on Asian casinos, particularly in Macau, where she claimed to have won AU$2.9 million at Galaxy Casino even after the Crockfords scandal.

Kelly has also begun teaching her techniques to students, raising the spectre of what she calls "an army of mini Kellys infiltrating mini-baccarat tables." She plans to focus more on poker, where her skills can be applied without legal controversy.

Her story has attracted Hollywood attention. In 2019, it was announced that actress Awkwafina would portray Kelly in a film adaptation, though the project remains in development. ESPN also produced an audio documentary titled A Queen of Sorts as part of their 30 for 30 podcast series, exploring her remarkable journey.

Kelly Sun's case has had lasting impacts on the gambling industry worldwide:

From her Las Vegas home—complete with walk-in closets overflowing with Jimmy Choo, Christian Louboutin, and Manolo Blahnik shoes, limited-edition handbags from Louis Vuitton and Hermès, and that money-green crocodile purse gifted by Phil Ivey—Kelly reflects on her journey with characteristic calm.

"I'm very happy to beat the casinos, but not excited," she says. "I feel satisfaction but not necessarily joy. This is work, and I am a professional. It's what I have trained myself to do. I do not feel bad if I lose, and I do not feel emotions if I win."

For Kelly Sun, the girl who once wore cardboard shoes in Northern China, beating the world's most sophisticated casinos for tens of millions wasn't about emotion—it was about mathematical precision, psychological manipulation, and the relentless pursuit of an edge. Whether you call it genius or cheating, there's no denying that Kelly Sun changed casino gambling forever.

"I never thought about being famous," she concludes. "I am very quiet. I don't say anything. I just want to beat casinos."

And for several years, she did exactly that—to the tune of over AU$44 million.