Sicilian Defence, Chekhover Variation

The Sicilian Defence, Chekhover Variation (also sometimes called the Szily Variation or Hungarian Variation) is a chess opening named after Vitaly Chekhover, from the game Chekhover–Lisitsin, Leningrad 1938. It is defined by the moves:
On move four White ignores the standard opening principle to not develop the queen too early in the game. Although the Chekhover Variation is somewhat rare at grandmaster level, it is not uncommon among amateurs.
The "Encyclopaedia of Chess Openings" (ECO) assigns code B53 to this opening.
Main line: 4...Nc6.
Black's main response to the Chekhover Variation is 4... Nc6 immediately attacking White's queen, leading to:
Example games.
Evgeni Vasiukov vs Loek van Wely, 2002
Mikhail Tal vs Robert Eugene Byrne, 1976