Lee Sedol (born 1983) is a South Korean professional Go player, widely regarded as one of the greatest players in the history of the game. He rose to prominence in the early 2000s, winning numerous world championships and becoming a 9-dan professional. Sedol is best known for his intense, creative, and aggressive playing style, as well as his historic 2016 match against Google DeepMind’s AlphaGo, which drew global attention to artificial intelligence and the game of Go. He retired from professional play in 2019.
1 Early life and education
1.1 Birth and family background
Lee Sedol was born on March 2, 1983, in Buan County, North Jeolla Province, South Korea. He was the third child in a family that had no prior connection to professional Go. His father, Lee Jae-hong, was a businessman who later took an active role in supporting his son’s early training.
1.2 Introduction to Go
Lee Sedol began learning the game of Go at the age of five, initially taught by his father. He showed remarkable aptitude and was soon enrolled in a local Go school. By age seven, he had won several junior tournaments in South Korea, prompting his family to consider a professional career.
1.3 Early prodigy years
In 1995, at the age of 12, Lee Sedol became a professional Go player after passing the rigorous Korean Baduk Association examination. He studied under the guidance of master coaches, including the renowned Lee Chang-ho’s former teacher, and rapidly climbed the amateur and junior professional ranks. His early style already hinted at the aggressive, fighting-oriented approach that would later define his career.
2 Professional career
2.1 Rise to prominence (2000–2005)
2.1.1 First world championship
Lee Sedol won his first major world title in 2002 at the Fujitsu Cup, defeating his senior compatriot Lee Chang-ho in the final. This victory announced his arrival as a top-tier player and marked the beginning of a generational shift in Go.
2.1.2 Rivalry with Lee Changho
Throughout the early 2000s, Lee Sedol developed a fierce rivalry with Lee Chang-ho (often called “Lee Changho”), the reigning world champion who had dominated the 1990s. Their matches, notably in the LG Cup and Samsung Cup, were intensely competitive and widely followed by Go enthusiasts. Sedol’s aggressive style contrasted sharply with Chang-ho’s calm, territorial approach, creating a dynamic that captivated fans.
2.2 Peak years (2006–2015)
2.2.1 Major tournament victories
2.2.1.1 Samsung Cup (2006, 2007)
Lee Sedol won the Samsung Cup in 2006, defeating Chinese player Chang Hao in the final. He successfully defended the title in 2007, defeating another Chinese opponent, Pu Xueting. These victories cemented his status as the world’s number one player.
2.2.1.2 LG Cup (2008, 2010)
In 2008, Lee Sedol won the LG Cup by defeating Korean player Won Seong-jin. He claimed his second LG Cup in 2010, overcoming Chinese player Kong Jie. These wins added to his growing collection of world titles.
2.2.2 Playing style and innovations
2.2.2.1 Aggressive territorial approach
Lee Sedol’s playing style emphasized direct, fighting-oriented moves aimed at securing territory quickly. He often engaged in complex, tactical battles from the opening, favoring sharp sequences that forced opponents into difficult calculations. This approach was sometimes criticized for lacking the philosophical depth of traditional Go, but it proved highly effective.
2.2.2.2 Unorthodox opening strategies
Sedol frequently employed unusual opening moves, such as the “three-three point” (tengen) and other non-standard placements, to destabilize opponents accustomed to standard patterns. His creativity in the early stages of the game was a hallmark of his peak period.
2.3 The AlphaGo match (2016)
2.3.1 Background and buildup
2.3.1.1 Challenge issued by DeepMind
In early 2016, Google DeepMind’s artificial intelligence program AlphaGo challenged Lee Sedol to a five-game match. AlphaGo had previously defeated European champion Fan Hui in October 2015, but the match against Sedol was seen as the true test of AI’s ability to surpass human mastery in Go.
2.3.1.2 Public anticipation
The match generated immense global media attention, as it was widely considered a “last bastion” for human intelligence against AI in board games. Go’s complexity—far exceeding chess—made the contest a milestone in artificial intelligence research. The prize was $1 million, donated to charity if AlphaGo won.
2.3.2 Match overview
The match was held in Seoul, South Korea, from March 9 to March 15, 2016. Each game was played under standard Korean tournament rules with a two-hour main time and three 60-second byoyomi periods.
2.3.2.1 Game 1: Loss
On March 9, AlphaGo defeated Lee Sedol in Game 1. Sedol played a standard opening but was gradually outplayed in the middle game. The loss shocked the Go community, as many had expected Sedol to win easily.
2.3.2.2 Game 2: Move 78 and victory
In Game 2, Sedol staged a stunning comeback. His famous Move 78 (a wedge into a weakness in AlphaGo’s position) was later praised as a “divine move” that forced the AI into an unforeseen sequence. Sedol won by resignation after AlphaGo’s apparent confusion. This victory remains one of the most celebrated moments in competitive Go.
2.3.2.3 Games 3–5: Consecutive defeats
AlphaGo won Game 3 with a powerful attack, exploiting a mistake by Sedol. In Game 4, Sedol played aggressively but lost after a late miscalculation. Game 5 was the closest, but AlphaGo once again prevailed. The final score was 4–1 in AlphaGo’s favor.
2.3.3 Aftermath and legacy
2.3.3.1 Impact on Go community
The match revolutionized Go. AI analysis tools became standard for training, and many professional players adopted new strategies inspired by AlphaGo’s insights. The public interest in Go surged, particularly among younger generations in China and South Korea.
2.3.3.2 AI and human collaboration
Lee Sedol himself later acknowledged the value of AI, stating that it helped players learn new patterns. However, he also expressed concern that the human element of creativity and intuition was being overshadowed. The match spurred discussions on the future of human-AI interaction in games and beyond.
2.4 Later career (2017–2019)
2.4.1 Final tournament wins
After the AlphaGo match, Lee Sedol continued to compete. He won the 2018 Hwangyongsa Cup (a Korean domestic tournament) and the 2019 Jipyeong Cup, a senior invitational for players over 30. These were his last major titles.
2.4.2 Retirement announcement
On November 19, 2019, Lee Sedol announced his retirement from professional Go. In a press conference, he cited the rise of AI as a primary reason, stating that he no longer felt he could compete at the highest level against both humans and machines. The news was met with widespread respect and nostalgia.
3 Playing style and contributions
3.1 Aggressive and intuitive style
Lee Sedol’s style is characterized by a relentless, attacking approach. He preferred complex, tactical fights over quiet positional play, relying on his sharp calculation and intuitive sense for life-and-death situations. This made his games dramatic and highly entertaining.
3.2 Notable innovations
3.2.1 "Sedol's wedge" and other moves
The wedge at Move 78 in Game 2 against AlphaGo is his most famous innovation, but he also popularized the “Sedol-jung” (a specific joseki variation) and several unconventional opening sequences. His willingness to experiment inspired a generation of players to think outside standard patterns.
3.3 Influence on modern Go
Sedol’s aggressive style influenced many young professionals, particularly in South Korea and China. After the AlphaGo match, his games were studied extensively by AI-assisted analysis, leading to new strategic understandings. He is credited with helping to modernize Go by challenging traditional norms.
4 Personal life
4.1 Family and relationships
Lee Sedol married his long-time girlfriend, Kim Hyun-jung, in 2009. The couple has two children. His family has remained largely out of the public eye, though he occasionally mentions their support in interviews. He also maintains close ties with his older brother, Lee Sang-hun, an amateur Go player.
4.2 Interests outside Go
Sedol is known to enjoy reading, particularly history and philosophy books. He has also been an avid fan of baseball and occasionally plays online games. Since retirement, he has focused on personal projects, including writing and giving lectures on Go and AI.
5 Awards and honors
- 9-dan professional ranking (achieved in 2003)
- 18 world championship titles (including 5 Asian Games gold medals in 2010)
- Samsung Cup: 2006, 2007
- LG Cup: 2008, 2010
- Fujitsu Cup: 2002
- BC Card Cup: 2009, 2010
- Korean Baduk Association Player of the Year (multiple times)
- Received the Cheongnyang Medal (a Korean cultural award) in 2016
6 See also
- Go
- AlphaGo
- Lee Chang-ho
- DeepMind
7 References
- Lee Sedol’s official Korea Baduk Association profile
- “The AlphaGo Match: A Retrospective” by DeepMind, 2016
- “Lee Sedol: The Last Human” – documentary (2017)
- Various tournament records from the Korean Baduk Association