India, April 12 -- It's a thing with R Vaishali. If she's on a winning run, she can be an unstoppable force. In Round 11 on Saturday, the 24-year-old appeared to be playing out a peaceful game with the Black pieces against Aleksandra Goryachkina. The Queens had been exchanged, Vaishali had a comfortable position, White had no ambitious plans, and a draw seemed the most likely result.

Vaishali, with a half-point lead at the top, didn't necessarily need to conjure up action on the board. But Vaishali chose to do Vaishali things. She set up a clever trap for White's rook and her unsuspecting opponent walked right into it.

The Russian played 30.Bc4 - the most natural move in the position. The evaluation bar vociferously disagreed. The blund...