|Moves||1.e4 g6 2.Bc4 Bg7 3.Qf3 e6 4.d4 Bxd4 5.Ne2 Bg7 6.Nbc3|
The Monkey's Bum is a variation of the Modern Defense, a chess opening. Although it may also be loosely defined as any approach against the Modern Defense involving an early Bc4 and Qf3, threatening "Scholar's mate", it is strictly defined by the sequence of moves:
The Monkey's Bum Deferred is a more respected variation in which White develops his queen's knight before playing Bc4 and Qf3.
The Monkey's Bum was discovered and championed by IM Nigel Povah in the 1970s during a wave of popularity for the Modern Defence. In 1972, after Keene and Botterill published their book The Modern Defence, Povah began looking for a response to the opening. He happened across the game Ljubojević-Keene, Palma de Mallorca 1971, which started 1.e4 g6 2.d4 d6 3.Bc4 Bg7 4.f4 Nf6 and eventually ended in a draw. Intrigued by Ljubojević's early Bc4, Povah began investigating a rapid assault on f7 with 3.Qf3. When he showed the first few moves to Ken Coates, a friend at Leeds, Coates declared, "If that works then I'm a monkey's bum!" The name stuck. The Monkey's Bum first appeared in print five years later in the British Chess Magazine. Povah wrote an article on the theory of the Monkey's Bum, in which he stated that although he had never yet lost with the variation, it was still "in its infancy".
In playing the Monkey's Bum, White's idea is to gain active piece play by a sacrifice of the d4-pawn, much like the Smith-Morra Gambit. In practice however, such compensation proves tenuous in the Monkey's Bum proper, as evidenced by the following game:
A much more popular and respected approach against the Modern Defense is the Monkey's Bum Deferred. It has been employed by such notable grandmasters as John Nunn, Sergei Rublevsky and Judit Polgár. It is distinct from the Monkey's Bum proper in that the attempt to create the "Scholar's mate" threat with Bc4 and Qf3 only occurs after White has developed his queen's knight. A typical sequence of the Monkey's Bum Deferred is 1.e4 g6 2.d4 Bg7 3.Nc3 c6 4.Bc4 d6 5.Qf3 (see diagram). Usually White will castle kingside and undertake an attack by means of the pawn thrust f2-f4.
The following spectacular game is probably the most famous success of the Monkey's Bum Deferred and forced it to be considered with respect by the chess world: