After 4 rounds GM Anand is leading Morelia-Linares with 3/4. Playing the black side of a Ruy Lopez against the Anand probably sounds as the closest thing to a slow torture, particularly if you choose one of the main lines, like Morozevic did. However, the Russian GM defended solidly and at one point could have obtained a slight initiative. The position after white's 31st move is critical. 31...Bh6! seems like an improvement. I have annotated the game and you can download it here: anandmoro.cbv or see it without comments:

(3) Anand,V (2779) - Morozevich,A (2741) [C95]

XXIV SuperGM Morelia/Linares MEX/ESP (4), 21.02.2007

[pgn] 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 d6 8.c3 0-0 9.h3 Nb8 10.d4 Nbd7 11.Nbd2 Bb7 12.Bc2 Re8 13.Nf1 Bf8 14.Ng3 c6 15.Nf5 Qc7 16.dxe5 dxe5 17.Nh2 c5 18.Qf3 c4 19.Bg5 Re6 20.Rad1 Nc5 21.Bxf6 Rxf6 22.Ng4 Re6 23.Nge3 Qa5 24.a3 g6 25.Nd5 Rd8 26.Qg3 Rd7 27.Nfe3 Qd8 28.Qf3 Bg7 29.a4 Red6 30.axb5 axb5 31.g4 Qh4 32.Ra1 Ne6 33.Qg3 Qxg3+ 34.fxg3 Nc5 35.h4 h6 36.Ra5 Bc6 37.Nb4 Bxe4 38.Bxe4 Nxe4 39.Rxb5 Nd2 40.Kg2 e4 41.Re2 Bf8 42.Ned5 e3 43.Nxe3 Re6 44.Nbd5 Nb3 45.Nf4 Rc6 46.Nxc4 Rxc4 47.Rxb3 Kg7 48.Rb5 Bc5 49.g5 hxg5 50.hxg5 Be7 51.Kf3 Bd8 52.Re4 Rc6 53.Kg4 Rd2 54.Rd5 Rxd5 55.Nxd5 Re6 56.Rxe6 fxe6 57.Nf4 Kf7 58.Nd3 Bc7 59.Kf3 1-0 [/pgn]