Mikhail Gurevich vs. Yefim Geller and Zwischenzugs

     The tournament in which this game was played, the Helsinki Open in 1992, was an incredibly strong event. GM Vladimir Tukmakov and GM Valeriy Neverov both scored 7-2 with Tukmakov winning on tiebreaks. Out of 116 players both Gurevich and Geller finished tied for 33rd to 54th at 5-4. 
     Geller needs no introduction, but Mikhail Gurevich is not so well known. He is not to be confused with the other Gurevich GMs: Dmitry, Ilya and Vladimir. Or, the IM, Daniel.
     Mikhail was one of Kasparov’s seconds in his many World Championship matches with Karpov and was a top ten ranked player from 1989–1991. He was also a second to Anand in the 1990s. He became a GM in 1986 and is currently an FIDE arbiter and senior trainer. 
     He was born February 22,1959 in Kharkiv, USSR, lived in Belgium from 1991 to 2005 (after the breakup of the Soviet Union), and since 2006, resides Turkey. 
     Gurevich was the USSR Champion in 1985, winning on tiebreaks after a three way playoff with Alexander Chernin and Viktor Gavrikov where all the games were drawn. He was not allowed to leave the country to participate in the Interzonal and Gavrikov and Chernin went in his place. 
     At the Manila Interzonal in 1990 the top eight finishers would qualify for the Candidates Matches. After round 11 (out of 13) Gurevich was in clear first and it was a forgone conclusion that he was going to qualify, but then disaster struck. In round 12 he lost to Anand after having gotten a slightly better position. Needing only a draw to qualify, he lost to Nigel Short in the last round and didn't make the cut. He never again reached the highest levels and his rating slowly fell as he first dropped out of the world's top 50 then top 100. Today he has a "lowly" 2555 FIDE rating. 
     The following game has a neat Zwischenzug at the end. A Zwischenzug is an in-between move - a move that is made in between the expected sequence. Geller sacrificed a piece then played a natural followup then made an outright blunder when he missed Gurevich's Zwischenzug. Zwichenzugs must meet two criteria. First, it has to be sufficiently forcing so that it prevents the intended sequence from occurring. If the opponent can ignore it, it's useless. e.g...a spite check just to prolong the game is not a Zwischenzug. Second, the Zwischenzug must prevent the intended sequence.