Just when he was sitting pretty with a black-piece win against arch-rival Veselin Topalov [ Images ] of Bulgaria, Anand was in for the biggest surprise of this season as Bacrot, once the youngest Grandmasters in the world, played energetically to catch the Indian ace off guard and score one of the biggest wins of his career.
Meanwhile, Magnus Carlsen [ Images ] of Norway salvaged some anxious moments and finally played out a draw with Vugar Gashimov of Azerbaijan, while in the other game of the day Topalov too could not make any headway and had to split the points with Wang Yue of China.
With six rounds to come in this six-player double round robin tournament, Carlsen took his tally to three points and he is now followed by Bacrot a half point behind.
Anand now stands sole third on two points while Topalov, Wang Yue and Gashimov are sharing the fourth spot on 1.5 points apiece.
It turned out to be a tough day for Anand in the Slav defence game wherein the Indian went for a well-analysed piece sacrifice variation.
As is typical of the opening, Anand got four pawns in exchange for his piece, but the nature of black pawns remained fragile.
To Bacrot's credit, he went for a relatively less played system, which should have been equal but Anand was caught off-guard in the exchanges that took place intermittently leading to a two pawn deficit for the Indian.
Technically, things were not easy but Bacrot did not let the opportunity slip and won in 46 moves.
Carlsen was also made to sweat for once. Playing white, Gashimov was seen pressing for an advantage in the middle game arising out of a Breyer variation in the Ruy Lopez that Carlsen has been frequenting these days.
After a methodical king side pressure, Gashimov shifted his gaze on the other flank and successfully weakened a couple of black pawns. Carlsen had to part with a pawn and he finally secured the half point with some perfect defence.
The longest game of the day lasted 76 moves.
Earlier, Topalov found nothing worthwhile with white against Wang Yue in a Slav defence game.
Facing a side variation early, Topalov went for uncompromising play but the Chinese was quite up the task in the middle game. Topalov won a pawn after trading the queens but there was a lot of pressure on his pawns that forced the sharing of points.
Results of round IV: Etienne Bacrot (Fra, 2.5) beat V Anand (Ind, 2); Vugar Gashimov (Aze, 1.5) drew with Magnus Carlsen (Nor, 3); Veselin Topalov (Bul, 1.5) drew with Wang Yue (Chn, 1.5).