In 1941, Vasily Smyslov was no longer a teenager and was gaining lessons from many of the top players in the world. The second world war put an end to international chess competition for several years. For players in the Soviet Union, however, opportunities remained. The USSR had far more than its share of future grandmasters (a title FIDE created in 1949). Young Smyslov took some lumps in the Absolute Championship of the Soviet Union, played in March and April in Leningrad and Moscow.
Smyslov earned a reputation as an extraordinary endgame player. Perhaps this lesson from Paul Keres helped him develop such skills.
Black to move
Keres played 30...Ne4+.
After a sequence of exchanges, Smyslov found himself in a rook endgame where he was forced into passive defense. In time, Black broke through.
31.Kg2 Rxe7 32.fxe4 Rxe4 33.Rxe4 dxe4 34.Rxe4 Rb5 35.Re2 (White's rook takes a passive defensive position) ...Rb3 (Black's rook restrains the White king).
White to move
Black has slightly better pawn structure, an aggressively placed rook, and a mobile king. Does Black have a decisive advantage?
The entire game is replayable at http://blog.chess.com/view/the-active-rook.
Checkmate in 3
48 minutes ago