11-15 23-19, 8-11

11-15 is the strongest opening move by Black as evidenced by its use 95% of the games played between experts in go-as-you-please (GAYP = unrestricted) play. Black exits from a single corner, as opposed to a double corner, which leaves the back row more vulnerable to kingship. Also, 11-15 is a move towards the board center for maximum mobility. 11-15 is so strong that more responses have been used by White to obtain equality than in any other opening. Nevertheless, irrespective of the reply to 11-15, Black has a small theoretical edge, although all result in equality with best play. 22-18 ("Single Corner"), 23-19 and 23-18 are the strongest replies, while 22-17 is only adequate. 24-20 ("Ayrshire Lassie"), 24-19 and 21-17 are inferior.

23-19 is a popular reply among all classes of players and 8-11 is Black's strongest second move.

• 19-16 11-20
(wins)
• 21-17 9-13
(wins)
• 22-17 9-14
• 22-18 15-22, 25-18 4-8
• 22-18 15-22, 26-17 11-16
(wins)
• 24-20 15-24 -> 11-15, 27-24 4-8
(wins)
• 24-20 15-24 -> 11-15, 32-28 15-24 -> 7-11
(wins)
• 24-20 15-24 -> 11-15, 19-16 12-19
(wins)
• 24-20 15-24 -> 11-15, other
(wins)
• 26-23 4-8
• 27-23 9-13