11-15 22-18, 15-22 25-18, 12-16

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.

22-18, called "Single Corner", is a popular reply used by experts because it leaves the pieces evenly balanced and leads to many excellent combinations. However, it is not much used by novices because it requires skilled play. Of the two forced response, 25-18 is much stronger than 26-17 and therefore much more common. 26-17 is seldom seen in serious play.

• 18-14 10-17 -> 9-18 -> 6-10
• 18-15 10-19 -> 7-11
• 21-17 9-14 -> 5-21
(wins)
• 23-19 16-23 -> 9-14 -> 5-14 (wins)
• 24-19 16-20
• 24-20 9-13 -> 8-22 -> 13-22 (wins)
• 26-22 16-20
• 29-25 9-13
• 30-25 10-14 (wins)