Going into the final stages of his World Championship match against Veselin Topalov in Sofia, Bulgaria, World champion Viswanathan Anand took radical measures to try to break the deadlock but after a six and a half hour struggle he could manage only a draw after the longest and most complicated game of the match so far.

The match remains tied at 4.5-4.5 with only three games remaining.

Anand had his opponent's king trapped on the back rank but with his last move before the time control on move 40 and with just three minutes thinking time left, Anand missed a chance to decide the game.

Missing out

After allowing Topalov's king to escape, it seemed that the World champion's winning chances had evaporated.

Now both players began to press for victory, Topalov's queen and running pawns fighting against Anand's active pieces.

Anand was gaining the upper hand but he was also running terribly short of time, with 10 moves to complete in only seven minutes to avoid a time forfeit.

He reached the move 60 time control and was out of danger of defeat, but the win still required extraordinary technique at a new time limit of 15 minutes plus 30 seconds per move for the remainder of the game. Eventually Anand erred and the game became completely random, with victory possible for either player.

Additional obstacle

Anand had an additional obstacle to overcome on Thursday as, while he was contemplating his 20th move, an electrical fault caused the lighting above the board to flash on and off, and then the main light failed completely.

Rather than stop the game timers, as the arbiter had done during the complete blackout in game five, Anand's clock continued ticking as he tried to maintain his concentration and find an effective plan.

Fortunately, only three minutes later full-strength lighting returned and Anand almost immediately gave away his queen for two lesser pieces.

Anand handled the resulting position with aplomb. However the game of the match continued, with the winner being hot favourite to take the world title. However, the deadlock remained intact.

The tenth game will be played on Friday.

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