Beware the Pointed Ones: Nimzo Exchange Sac in Kaidanov-Onischuk

Gregory Kaidanov (pictured) was born October 11, 1959 in Ukraine and moved to the United States from Russia in 1991. In 1988, he had become a grandmaster. In the U.S., he has kept active as a player and teacher of chess. Perhaps, his most impressive tournament victory was the Aeroflot Open in 2002. The following game is from the Chicago Open in 2002. Kaidanov ended in a seven way GM tie for first with 5.5/7.

Alexander Onischuk was born September 3, 1975 in Ukraine. He is also a grandmaster who moved to the United States, coming in 2001. He was the U.S. Champion in 2006. He plays in some of the top invitationals, such as at Biel 2007, where he scored 5.5/9 to tie with Magnus Carlsen for first, although he lost the tie-breaker match. In the Chicago Open, he scored 5/7, for places 8-15.

The opening of Kaidanov-Onischuk was the Nimzo-Indian Defense. The apparent Rubinstein Variation with 4.e3 became the Saemisch Variation after 5.a3. The sockdolager was the offer of an exchange with 14.Ra2!! which Black accepted. I found the game in Ivan Sokolov's fine “Winning Chess Middlegames: An Essential Guide to Pawn Structures” (2008) to attempt to understand the game. I offer more alternatives to what was played.