Sergey Karjakin of Russia scored his third straight victory at the expense of Wang Hao of China to lead the table with three points. Anand and Levon Aronian follow him, a full point behind.
Teimoru Radjabov of Azerbaijan finally won a game, disposing the challenge of local hopeful Jon Ludvig Hammer to move to a fifty per cent score.
With six rounds to come in the ten-player tournament, Radjabov shares the fourth spot along with world number one Magnus Carlsen of Norway, Hikaru Nakamura of United States and Russian Peter Svidler on 1.5 points apiece.
The day produced three decisive games and local star Carlsen had to settle for his third straight draw with Nakamura. Russian Svidler too shared the point with Aronian making sure he stayed in the hunt as well.
Anand produced his best when needed. Playing the white side of a Najdorf Sicilian, the Indian ace went for the English attack and came up with some startling new ideas that caught Topalov unawares.
It may be recalled that in 2010, a superior preparation had given Anand a victory in the last game of the world championship match against Topalov and the Bulgarian still doesn't seem to have recovered from that.