Who's the Grandmaster?

Speaking of great chess players who were never world chess champions, here’s a photo of a simul by a world-class grandmaster who actually coached two world chess champions. Can you guess who? More hints: He won the Soviet Chess Championship twice and was a Candidate for the World Championship on six occasions. You can find the answer and some more great photos in black and white at the Russian Chess Federation website. But, why not try guessing and we will post the answer in the comments tomorrow.