Improving the position of the bishop.

Otherwise the beastly bishop will dominate both white rooks on d3 .

Now White slipped up with . . . .

. . . and lost quickly after . . .

Reaching for the hole on d6 to become an octopus.

The immediate 20.Nd6 was also good.

With his last move Black had prepared 21 . . .Bf5 , so Grischuk decides to land the octopus. Within three moves White has established a big space advantage, which is practically winning.

. . . and White converted his advantage.