by James Sedgwick 6D
In the A division, Michael Xu scored two wins on Monday, solidifying his position as favorite to take the second spot in the group behind Bill Lin. The following sharp move was key to victory. First, Stephen played a slow move at the top (diagram at top right). It is worth a fair amount of points, but both black positions it cuts are very stable, so this move isn't a priority right now. Probably conscious of this, white ignored the normal sente at A (middle right diagram), and Michael didn't miss his chance, playing the very severe move at B. Stephen might have managed a ko, but even that would have given Michael a comfortable lead. In the game Stephen tried for more, and died cleanly.
Meanwhile in the B division, entering the afternoon things were very unclear.
Eric Lee played very skillfully, and built up a 7-point lead and the chance to play spoiler against Guanyu Song. Eric Lee should save his stones at A (diagram at left), but he was afraid of the cut that comes after C-D-E. If sente, the stone at B would help a lot! But in fact it isn't sente, and Guanyu didn't miss his chance, taking the two stones on the right in sente with a C/E exchange, and then cut at G. White can make some gains at the top, but not nearly enough, Guanyu has a large lead.
Meanwhile among the other contenders Eric Yoder played very solidly, and secured his two wins on Monday. So the battle between Sen Zhan and Tianyu Chen was key to who would join them at 3-1 in a good position to move through to the playoffs. Early on Sen chose to start a ko at the top. Winning it was larger than any compensation Sen could get, and Tianyi secured a decent lead. But these are both fighting style players. There is a dangerous cut at A (figure at bottom right). Tianyi could have defended directly, while making some points at the bottom; this would have been good enough to secure his lead. But he chose the more active game move shown. This move is extremely large, and opens up many weaknesses in Sen's position, which Tianyi expected to use to manage the cut. But in the end it was an extremely complex fight, in which Sen came out on top, moving to 3-1, and earning a good shot at a B division playoff spot.