A pity more people didn't try this one because it is, as Stick put it, very cute. I played 21/20 3/1* and although I was not sure of the play, I was certainly startled when XG World Class analysis said that 21/20 5/3 was ahead by about 0.04! A full rollout narrowed the gap considerably but 5/3 is still on top. If I had been given this position and asked to find the bot play, I doubt that I would have gotten it in three tries. I can come up with some reasons for it but certainly not convincingly enough to be able to find a similar play OTB next time. Any thoughts?
  White is Player 2
score: 4 pip: 133  7 point match  pip: 147 score: 3
Blue is Player 1  
XGID=aABDABcCbcdAAb:0:0:1:21:3:4:0:7:10 
Blue to play 21 
1.  Rollout^{1}  21/20 5/3  eq: 0.047 
 Player: Opponent:  45.47% (G:11.92% B:0.52%) 54.53% (G:12.83% B:0.65%)  Conf.: ± 0.009 (0.056...0.039)  [99.1%] Duration: 1 hour 25 minutes 

2.  Rollout^{1}  21/20 3/1*  eq: 0.062 (0.015) 
 Player: Opponent:  44.67% (G:12.24% B:0.54%) 55.33% (G:13.26% B:0.68%)  Conf.: ± 0.009 (0.071...0.054)  [0.9%] Duration: 1 hour 26 minutes 

3.  Rollout^{2}  21/20 13/11  eq: 0.093 (0.046) 
 Player: Opponent:  44.29% (G:11.10% B:0.49%) 55.71% (G:12.62% B:0.64%)  Conf.: ± 0.018 (0.111...0.075)  [0.0%] Duration: 21 minutes 52 seconds 

4.  Rollout^{2}  21/20 8/6  eq: 0.136 (0.089) 
 Player: Opponent:  43.59% (G:10.74% B:0.50%) 56.41% (G:11.33% B:0.47%)  Conf.: ± 0.016 (0.152...0.120)  [0.0%] Duration: 19 minutes 40 seconds 

5.  Rollout^{2}  6/3  eq: 0.162 (0.115) 
 Player: Opponent:  44.95% (G:13.17% B:1.18%) 55.05% (G:23.12% B:1.51%)  Conf.: ± 0.016 (0.179...0.146)  [0.0%] Duration: 17 minutes 52 seconds 


^{1} 5184 Games rolled with Variance Reduction. Dice Seed: 271828 Moves: 3ply, cube decisions: XG Roller
^{2} 1296 Games rolled with Variance Reduction. Dice Seed: 271828 Moves: 3ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2