With eight games still to come in the 12-game affair, the scores are tied at 2-2 and the battle is really heating up if the last two games are any indication.
Anand was pushed to the wall for the first time in the match and this happened soon after he was seen pressing for a win in the third game that ended in a draw yesterday. It showed that Carlsen has got steely nerves.
The Berlin defense became famous after Vladimir Kramnik used it successfully to beat Russian compatriot Garry Kasparov in the Braingames World Championship match in 2000 at London and since then it has found a stronghold in the elite chess circles.
Anand himself has played the opening with black successfully and he definitely had an idea up his sleeves. However, Carlsen was the first to spring a surprise as early as on move 10 when he moved his Bishop.
Anand did not get much out of the opening and, while looking for complications, sacrificed a pawn on the queen side, that to the bare eye looked like a poisoned pawn.
Known to never avoid complications, Carlsen took the bait and it was backed by some brilliant intuition as the later part of the game revealed.