1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 d6 6.Bg5 e6 7.Qd2 a6 8.0-0-0 Be7 9.f4 Nxd4 10.Qxd4 b5 11.Be2 Bb7 12.f5 e5 13.Qd3 b4 14.Bxf6 bxc3 15.Bxg7 Rg8 16.f6 Bxf6 17.Bxf6 cxb2+ 18.Kb1 Qxf6 19.Rhf1 Qe6 20.Bh5 Rf8 21.Rxf7 Rxf7 22.Rf1 0-0-0 23.Bxf7 Qd7 24.Bd5 Qb5 25.Qxb5!?
In light of the result of the game, it is easy to second guess this decision. However, White gets a somewhat favorable endgame where she can press for a win with hardly any risk of losing. Against an opponent like Kramnik, that is a very tempting prospect!
25.Qc3+
Qc5
26.Bxb7+
Kxb7
27.Rf7+
Kc6
28.Qb3
is rather uncomfortable for Black.; 25.c4
Qb6
26.Rf7
Bxd5
27.cxd5
also leaves Black under uncomfortable pressure.
25...axb5
26.Bxb7+
Kxb7
27.Rf7+
Kc6
28.Rxh7
d5!
Black is seriously worse in this ending. What he needs is a trump of his own, and he manufactures that trump right now by creating a passed e-pawn.
29.exd5+
Kxd5
30.Kxb2
Kd4
31.g4
e4
32.Re7
Ke3
33.h4
In hindsight this is just a bit too slow. 33.g5! Passed pawns must be pushed! Of course, White can only afford to do this because the pawn can reach g7 where it will tie down Black's Rook completely.
Play might continue 33...Kf3
(33...Rh8
allows Black to win both of White's kingside pawns for his e-pawn, but the price is too high: Black's King gets locked out of play. 34.g6
Rxh2
35.g7
Rg2
36.Kc3
Kf3
37.Kd4
Rg4
38.a3
Kf2
39.Rxe4
Rxg7
40.Kc5
Rg5+
41.Kb4
Kf3
42.Re8
Kf4
43.a4
bxa4
44.c4
Kf5
45.Kxa4
Kf6
46.Kb4
Kf7
47.Re1
Rg8
48.c5+-
) 34.Rf7+
Kg2
35.g6
e3
36.g7
e2
37.Rf8
Rxf8
38.gxf8Q
e1Q
39.Qf4+-
and White has excellent winning chances.
33...Kf4
34.g5
Rh8
35.g6
Rxh4
36.g7
Rg4
37.Kc3
Kf3
38.Kd4
b4
39.Kc4
39.c3!?
would be another winning try, e.g. 39...bxc3
40.Kxc3
e3
(40...Kf2
41.Rxe4
Rxg7
42.a4+-
and Black's King is cut off by too many files, so White wins.; 40...Ke3
41.a4
Rg6
42.a5
Rc6+
43.Kb4
Rc8
44.a6
Kd4
45.a7
e3
46.Kb5+-
) 41.Kd3
e2
42.Rf7+!
Kg2
43.Kxe2
and Black is hopelessly lost.
39...Ke3
Since White is going after the b-pawn -- which must be removed in order for the other queenside pawns to run -- Black transfers his King across in front of his pawn. This might seem odd, but it makes sense because on d2 the King will shoulder off White's King. That means that White will have to fight against Black's e-pawn with the Rook alone, unaided by her King. And that contest is what Andy Soltis calls a "mismatch": White will have to sacrifice the Rook for the pawn.
40.Kxb4
Kd2
Now the Black King is in the perfect position to shoulder off White's King and shepherd the e-pawn home.
41.c4
e3
Still hurrying forward.
43.c5
Rxg7!
A little trick that is the prerogative of anyone who has a pawn on the seventh threatening to Queen.
44.Rxe2+!
Fortunately, Black's King is much too far away to stop the White pawn.
44...Kxe2
It takes White five moves to "queen" the c-pawn: two to get the King to b7 where it controls c8, and three for the pawn itself. But it takes Black many more to control c8 with both King and Rook. So Black's Rook will have to be sacrificed for the c-pawn, leaving an ending where Black's King is in time to catch the White a-pawn.
45.Kb6
For a moment, Black might almost panic here and wonder if he were losing after all. But Kramnik knows that everything is under control.
45...Kd3
The King comes up the diagonal -- the shortest route toward the zone of action where the White King is and the pawns are about to be.
46.c6
46.a4
Kc4
47.c6
Kb4
48.a5
Rg5
49.a6
Rb5+
50.Kc7
(Or, with a curious parallel of ideas, 50.Ka7
Ka5
51.c7
Rc5=
) 50...Kc5
51.a7
Ra5
and both of White's pawns come off.
46...Kc4
47.c7
Rxc7!
Simplest. Black has counted and knows he can catch the White a-pawn.
48.Kxc7
Kb4!
49.Kb6
1/2-1/2