With this, Carlsen is two points up against Anand and in a strong position to wrest the title from the Indian.
"I got a solid position in the opening," Carlsen told the media after the game. According to him, the pawn sacrifice by Anand in his 44th move was a surprise. "I don't think a pawn could be given like that," Carlsen said.
Queried about his mood Carlsen said it is good to win two games. "With six games to go, it is a healthy lead," he said.
This loss meant Carlsen went two points up against the Indian Grandmaster
Anxious may be but not ambitious to play aggressively for a win, is the one liner that experts say about Anand's sixth game play.
Playing white, Anand opened the game pushing his king pawn two squares. Carlsen repeated the same with his king pawn. The subsequent moves resulted in what is called Ruy Lopez opening.
Anand's 10th move Bg5 pinning black's Knight made Carlsen go in deep thought about the plans the reigning world champ had up his yellow shirt sleeves. Moreover Anand is a wounded lion wanting to equalise the scores after his loss Friday.
"The Indian seemed to have come prepared with that move. Perhaps Anand was expecting Carlsen to play h6 to threaten the bishop. But Carlsen seems to have played strategically with Be6 though it is not an optimal move," India's number two ranked Grandmaster P. Harikrishna told IANS.
According to him, Carlsen's strategy till now is very clear. Steer Anand away from theory, pre-game preparations with some move and make his opponent tax his brain further on a new line(s).
In order to simplify things to some extent, Carlsen exchanged his white bishop to Anand's white bishop.
The game progressed steadily on an even keel with experts starting to predict a draw at the end of the 18th move though the major and minor pieces were on the board.
It seemed Anand was holding on to his pieces without trading so that he could put the challenger in a spot.
"But he cannot do so for long as Carlsen would have started to play for a win," Harikrishna said.
That is precisely what Anand did by going in for exchanging minor pieces. At the end of the 24th move, both the players had their two rooks, queens and seven pawns on the board.
Four moves later, both the players traded one of their rooks.
And Carlsen entered his comfort zone - the end game phase - where Anand has to fight till the last move to earn a draw if not a win.
On the 38th move, Anand moved his queen to g3 square so that despite going a pawn down, the game would be theoretically a draw in a rook ending.
Both the players traded their queens as well.
"It is a huge psychological play on the part of Carlsen. Even though the position is drawish, Carlsen will continue to play to make Anand to think four variations for each and every move. Tire your opponent out or drain your opponent's energy seems to the Carlsen's strategy," Harikrishna said.
While the game moved slowly, Anand made the surprise h5 move giving up his pawn.
"Perhaps Anand was trying for a zugzwang position (a situation where a player who makes the move ends up in a losing position)," R. Raghunathan, a former national player, told IANS.
Making deft King and rook moves, Carlsen forced Anand's King down. The challenger continued to trouble the champion move after move.
Further, Anand's King was cut off from the end game while Carlsen's King was active on the board.
The championship is being sponsored by the Tamil Nadu government.
At the end of the sixth round, Anand with two points is trailing
Carlsen who is on four points. The seventh game will be played
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. c3 O-O 6. O-O Re8 7. Re1 a6 8. Ba4 b5 9. Bb3 d6 10. Bg5 Be6 11. Nbd2 h6 12. Bh4 Bxb3 13. axb3 Nb8 14. h3 Nbd7 15. Nh2 Qe7 16. Ndf1 Bb6 17. Ne3 Qe6 18. b4 a5 19. bxa5 Bxa5 20. Nhg4 Bb6 21. Bxf6 Nxf6 22. Nxf6+ Qxf6 23. Qg4 Bxe3 24. fxe3 Qe7 25. Rf1 c5 26. Kh2 c4 27. d4 Rxa1 28. Rxa1 Qb7 29. Rd1 Qc6 30. Qf5 exd4 31. Rxd4 Re5 32. Qf3 Qc7 33. Kh1 Qe7 34. Qg4 Kh7 35. Qf4 g6 36. Kh2 Kg7 37. Qf3 Re6 38. Qg3 Rxe4 39. Qxd6 Rxe3 40. Qxe7 Rxe7 41. Rd5 Rb7 42. Rd6 f6 43. h4 Kf7 44. h5 gxh5 45. Rd5 Kg6 46. Kg3 Rb6 47. Rc5 f5 48. Kh4 Re6 49. Rxb5 Re4+ 50. Kh3 Kg5 51. Rb8 h4 52. Rg8+ Kh5 53. Rf8 Rf4 54. Rc8 Rg4 55. Rf8 Rg3+ 56. Kh2 Kg5 57. Rg8+ Kf4 58. Rc8 Ke3 59. Rxc4 f4 60. Ra4 h3 61. gxh3 Rg6 62. c4 f3 63. Ra3+ Ke2 64. b4 f2 65. Ra2+ Kf3 66. Ra3+ Kf4 67. Ra8 Rg1 0-1