Tuesday’s winning 5-second tactics

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TURN AROUND…
gm Kovalenko, Igor (2650)
im Abdulov, Orkhan (2344)
Baku Open 2014.9.22 Yesterday. Position after White’s 38th move (38.Re3). A curious fight, White being on the defensive since virtually the opening stage but somehow managing to hold on; Black feeling compelled to win, being 300-plus rating points higher rated, sacrificed a piece for several pawns but only giving compensation in an unclear game.
Here Black should play to simply hold the game with 38…h4!?, and after 39.PxP Qc5!, ready to harrass the White King with …Qc7 Analysis indicates that the game should probably end in a draw, White not being able to make progress as his pieces are jumbled and he has only two pawns left.
HOWEVER, Black wanted more…
38…Nc5?

Intensifying the pressure on White’s pieces.
WHITE TO PLAY AND WIN!
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THE WRONG ROOK!
gm Zhigalko, Sergei (2677)

im Aghasiyev, Kamal (2374)
Baku Open 2014.9.22 Position after White’s 36th move (36.Ne5) attacking the f7-pawn. The game is dynamically balanced, with both sides having chances. For now, Black must deal with the attack on f7. Advancing …f6 or …g6 are out of the question, so that leaves Black with the choice of …Ra7 or …Rc7. But which one?
After the game it was determined that 36…Rc7 was correct and sufficient to maintain the balance: 37.Rb4?! Ne4! or 37.Rb-c1 Qxb5! (Not 37…R8-c8? 38.RxN! RxR 39.Qf7+ Kh7 40.Nd7! winning) when 38.RxN!? RxR 39.Qxf7+ Kh7 is perpetual check, but not more.
INSTEAD, Black chose the other Rook…
36…Ra7?

A subtle error that White pounces upon immediately
37.Rb4!

Exploiting the small detail that Black does not have the blocking …Ne4 because the Rook on c8 is undefended (!), White shifts his Rook to the h-file and Black finds himself completely defenceless. The game continued logically:
37…f6 38.Rh4!

Black resigned a few moves later.
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