Amateurs versus Professionals
It should be noted that in several cases (the European or US tournaments) the professional opponent was away from active tournament play with other professionals. And in several cases the notable amateur player was an insei and/or later turned professional.
4th Xinren Wang 1997
1st Toyota Denso Cup World Go Oza
2002-09-02: Fernando Aguilar defeats Yo Kagen 9p in the 2nd round thus reaching the quarterfinals, where he lost by resignation against Lee Changho (2002-09-04).
Fujitsu Cup 2003
International representative against 5th Women's Saikyo
1st Pandanet Open Internet World Rapid Championship (IGS)
2005-03-19: Victor Chow defeats Sasaki Tsuyoshi 5p
Victor Chow was the only amateur to reach the 6th round, where he lost to Kono Rin 9p.
US Masters Tournament 2005
2005-06-13: Jie Li defeats Feng Yun 9p
2005-10-07: Jie Li defeats Huiren Yang 1p
US Masters Tournament 2006
2006-10-08: Jie Li defeats Mingjiu Jiang 7p
2006-10-15: Jie Li defeats Yilun Yang 7p
2006-10-18: Jie Li defeats Lin Xuefen 1p
2006-12-18 and 2006-12-19: Jie Li defeats Feng Yun 9p in the final of the 2006 US Masters Tournament with a score of 2-1.
LG Cup Preliminaries 2007
2007-04-26: Kim Jonghae defeats Yoo Jaeho 2p
2007-04-27: Kim Jonghae defeats Lee Daehyeoi 3p (but loses the final against Lee Heesung 7p thus not qualifying for main tournament)
Samsung Cup Preliminaries 2007
2007-07-31: Kang Changbae 6d defeats O Joosung 2p (but loses in the semifinals against So Yokoku 8p)
2009-02-23/24/25: The 20 (Korean) amateurs chosen by several preliminaries played in the mixed preliminaries with 236 professional players. With 0,9 (18/20) wins per player, 54,5% (18/33) winning rate and 25% (5/20) qualification rate they played (slightly) better than the professional players on average.
Preliminaries of 16th Agon-Kiriyama Cup
2009-02 and 2009-03: Amateur players won 20 games against professional participants. However, no amateur reached the last preliminaries, though some were quite close. ( results (japanese)) Amateur players had 17 wins in 2008 and only 8 in 2007.
Samsung Cup Preliminaries 2009
2009-08 Many Korean amateurs, including Yeonguseng compete in the preliminaries, scoring several wins against professionals. Lee Wonyoung defeats Kwon Omin 5p, Han Sanghoon 4p, Kang Jisung? 8p, and Han Wonggyu 2p, qualifying for the 32 player final tournament. The American representative Dae Hyuk Ko won his first game against Kim Jinwoo 4p.
2nd BCcard Cup World Baduk Championship 2010
2010-01: The 20 (Korean) amateurs chosen by several preliminaries played in the mixed final preliminaries winning 23 games. Five of them qualified for the main tournament. (Na Hyun, Choi Hyunjae, Park Yeongrong 박영롱, Lee Juhyung, Han Taehee). Han Taehee, a yeonguseng, defeated Lee Changho by resignation after only 96 moves in the first round!
Thus they were on average more successful than the professional players in the preliminaries. (And even more successful than last year.).
Preliminaries of 17th Agon-Kiriyama Cup
A bad year for amateurs, who won only ten games compared to 20, 17 and 8 in 2009, 2008 and 2007 respectively. (More here)
Samsung Cup Preliminaries 2010
2010-08 12 korean amateurs (including Yeonguseng) compete in the preliminaries, winning eight games against professional players. Min Sangyoun won three games straight, among others against Mok Jinseok, thereby qualifying for the main tournament.
Cho Insun beats Yun Jungsang? and Seo Gunwoo to make the main tournament, then beats Park Jeonggeun in the main tournament. Wang Jaeyung? qualifies for the main tournament as an amateur, is made professional before the first round (possibly by coincidence).
valerio: both are made professionals, by reaching the main tournament.
Several professionals reside outside Asia and participate regularly in go events there. Therefore they play against amateur players more often and sometimes lose to the strongest of them. (See also here and here)
- The Agon Cup allows both amateur and professional entrants, and sometimes the amateurs win their games. A few game records are available at Go4Go.
- Jimmy Cha also lost to Ted Ning and Thomas Ko in Fujitsu competitions. It is interesting to note that Michael Redmond only lost to fellow pros when he participated in the N.A. Fujitsu Qualifier - several times to Jimmy Cha, and once to James Kerwin.