A game with Mr Sham

Hi .. on 27 April 2011 Mr sham and i played 3 round of chess .. the first round we agreed on a draw . I played as black and it was Rook + Knight vs Rook + Bishop ending with each side having 2 pawn . On the second game I lost on a spectacular tactic by Mr Sham .. WOW ! it was good ( i played as white).

On the third game, I played as black using my trusty pirc defence meanwhile Mr Sham was using Austrian attack against me. And on move 5 he played a3 , that kind of puzzle me and i have to rethink my counter attack.
Well we played and reach below diagram ,


 I saw a mating opportunity

 1. ... Rxh3+  2. Kg1 Rg3 !! ( mating threat )
 3. Qxg3  fxg3  4. Bxf8
  











Now we reach this position .. could you see the mating move/ the winning move.



the move is 4. ..... Qe5+  5. Ka8 (Mr Sham move and he resign here) Qa5+  6. Kg1 Qa7#