Zurich Challenge G6: Exciting draw after 43 moves

[Event "Zurich Chess challenge Kramnik vs Aroni"] [Site "Zurich"] [Date "2012.04.29"] [Round "6.6"] [White "Aronian, Levon"] [Black "Kramnik, Vladimir"] [Result "1/2-1/2"] [ECO "C65"] [WhiteElo "2820"] [BlackElo "2801"] [Annotator "Ramirez,Alejandro/ChessBase"] [PlyCount "85"] [EventDate "2012.??.??"] 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Nbd2 d6 6. c3 O-O 7. O-O Ne7 8. h3 Ng6 9. Re1 c6 10. Ba4 Re8 11. d4 Bb6 12. Bc2 h6 {0.00/0 Kramnik is actually quite familiar with this position - he used it twice just last year against Radjabov in the Candidate's matches.} 13. a4 {-0.03/0} (13. Nf1 d5 14. Nxe5 Nxe5 15. dxe5 Rxe5 16. Bf4 Re8 17. e5 Nh7 {Brought Radjabov nothing in both games, as much as the computer likes White's position.}) 13... Be6 {0.00/0} 14. Nf1 {0.04/0 Since Black played Be6, d5 is no longer possible, but his position should be fine nonetheless.} exd4 {0.15/0} 15. Nxd4 {0.00/0} Bd7 {0.00/0} 16. f4 {-0.15/0} d5 $5 {0.19/0 The start of an interesting sacrifice.} 17. e5 {0.29/0} Ne4 {0.24/0} 18. Bxe4 {0.12/0} dxe4 {0.24/0 Black's pawn on e4 is doomed, but a funny thing about doomed pawns in chess is that they are annoying until actually taken. White can't really play Rxe4 so he must make some preparations.} 19. a5 $5 {0.00/0 Distracting the bishop, White hopes to take on e4 while retaining his strong pawn center.} (19. Ng3 f5 $13) (19. Rxe4 c5 20. Nf3 Bc6 $44) 19... Bxa5 {0.00/0} 20. Ng3 {0.04/0} Bb6 {0.00/0} 21. Kh2 {0.00/0} c5 {0.16/0} 22. Ndf5 { 0.24/0} Bxf5 {0.24/0} 23. Nxf5 {0.17/0} Qxd1 {0.16/0} 24. Rxd1 {0.13/0} Rad8 { 0.17/0} 25. Be3 {0.00/0 White is now the one that is down a pawn, but it seems certain that he will regain e4 eventually, and emerge with the better pawn structure. Black must play carefully.} Rd3 {0.11/0} 26. Re1 {0.00/0} f6 $1 { 0.00/0 Black breaks the center, giving up his h pawn but turning his doomed pawn into a supported passed pawn! Funny how quickly things change in chess.} 27. exf6 {0.00/0} gxf6 {0.00/0} 28. Nxh6+ {0.00/0} Kf8 {0.15/0} 29. Ra4 $1 {0.33/0 Fighting for the advantage. The e8 rook is now tied to e4.} Rd5 {0.31/0} 30. c4 {0.00/0} (30. Ng4 {seemed more logical to me.} Kg7 31. Bc1 {trying to Blockade. Maybe white has a little pull here.}) 30... Rd3 {0.00/0} 31. b4 $2 { -0.18/0 Black has several good moves here to retain equality, but Kramnik sees a chance to go for it.} Rxe3 $1 {-0.17/0} (31... cxb4 32. Bxb6 axb6 33. Rxb4 Nxf4 34. Rxb6 Kg7 35. Ng4 Rd2 36. Ne3 Rh8 37. h4 {leaves White with an advantage.}) (31... Nh4 32. Ng4 {does so too.}) 32. Rxe3 {-0.21/0} cxb4 {-0.15/ 0} 33. Rg3 $5 {-1.41/0 Seeking counterplay.} e3 $2 {-0.24/0 Missing a chance to win the match.} ({Fritz 13 and all engines in the Let's Check cloud were yelling for} 33... Ne7 $1 {This move is a little strange but it gave Black excellent winning chances. The knight is restricting two of White's pieces and the passed pawn will still roll. It's hard to believe White will survive, as Bc7 is also in the air.} 34. Rxb4 Bc7 35. Rg4 (35. Rxb7 $2 Bxf4 {is deadly.} ) 35... e3 {and White is in deep trouble.}) 34. Rxg6 {0.00/0} e2 {0.00/0} 35. Ra1 {-0.24/0} Bf2 {0.13/0} 36. Rg8+ {-0.15/0} ({In Let's Check Rybka and Houdini were proposing} 36. g4 e1=Q 37. Rxf6+ Kg7 38. Rxe1 Rxe1 (38... Bxe1 39. g5 Re2+ (39... b3 40. Rf7+ Kg6 41. Rf6+ {is a perpetual.}) 40. Kh1 Bc3 41. Rf7+ Kg6 42. Rxb7 {and Black can no longer win.})) ({Fritz 13 preferred} 36. Rxf6+ { first.}) 36... Ke7 {-0.25/0} 37. Rg7+ {-0.33/0} Kd6 {-0.21/0} 38. Rxb7 {-0.16/0 } e1=Q {-0.18/0} 39. Rxe1 {-0.33/0} Bxe1 {-0.13/0} 40. Nf5+ {-0.29/0} Kc5 {0. 00/0} (40... Kc6 41. Rxa7 b3 42. Nd4+ Kb6 43. Ra1 Bc3 44. c5+ Kc7 45. Nxb3 Bxa1 46. Nxa1 $11 {is very likely a draw since the knight can't actually be trapped. }) 41. Rb5+ {0.00/0} Kc6 {0.00/0} 42. Nd4+ Kc7 43. Rc5+ ({Aronian has found an amazing resource, as we could see on Kramnik's face in the live stream.} 43. Rc5+ Kb6 (43... Kd8 44. Rd5+ Ke7 45. Nf5+ Kf8 46. Rb5 {is in fact good for White.}) 44. Rb5+ Kc7 45. Rc5+ {and draw by perpetual.}) 1/2-1/2