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Here, each side made blunders, alternately with white losing the draw, and then black giving it back.

White maintains a draw with 70. Re7!, which gives his rook room to get behind the a-pawn and keeps the knight off f7 where it could stop white's h-pawn.

Instead white played <70. Re6?>, "attacking" the knight. But this allows black to defend the knight with the king AND gets his king off of the a1-a8 diagonal -- which will be important if a pawn race ensues. Black's best move is 70...Kc5!, where the king is able to escort his pawns.

Black missed the best move by playing <71...Kd5?>, allowing 72. Re1! b4 73. Ke3! b3 74. Kd2, and the king gets in front of the black pawns, which should draw since the black king is too far away at d5. (Had black played 70...Kc5, then he could reply to 74. Kd2 with 74...Kb4! and eventually ...Ka3, winning.)

White returns the favor with <72. Re5?>, a purposeless check that forces black to go where he wants to go: to c4 -- but black doesn't go there! Instead he playes <72...Kd4?>, again missing the opportunity to support his pawns, and worse, putting his king back on the a1-a8 diagonal.

Now, white finds <73. Re7!>, which should draw. <73...Ra7 74. Ra7 Nb5> (diagram:white to move):

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Here, white should draw easily with 75. h5! b3 76. h6 b2 77. h7 b1=Q 78. h8=Q+! In fact, black could even lose if he blunders by taking the rook (75...Nxa7? 76. h6 a2 77. h7 a1=Q 78. h8=Q, winning black's new queen with a skewer ).