Viswanathan Anand scored a crushing victory over Alexei Shirov of Spain in the 10th round to maintain his position at the top in the 73rd Tata Steel chess tournament in Wijk Aan Zee.
Anand's victory came about the same time when American Hikaru Nakamura triumphed over Maxime Vachier-Lagrave and the two maintained their co-leader status moving to an identical seven points out of a possible 10.
In another major surprise of the tournament world number one Magnus Carlsen suffered his second defeat with white pieces in the tournament bowing to Russia champion Ian Nepomniachtchi in a hard fought game.
The other two over night leaders Vladimir Kramnik of Russia and Levon Aronian of Armenia played out draws with Dutch duo of Jan Smeets and Anish Giri respectively to remain a half point behind the two leaders.
With just three rounds to come it remains crowded at the top and it seems a close call between the top four placed players.
Carlsen, after the devastating loss, shares the distant fifth spot with Vachier-Lagrave and Nepomniachtchi on 5.5 points and will now need a miracle to find himself in the leading group.
Anand faced the Slav defense against Shirov who played black and quite nonchalantly gained the upper hand in the complexities that arose in the middle game.
Shirov was off-form here and this game was another attestation to the fact as the Spaniard missed some fine prints and landed himself in troubles.
Anand took his chances and was rewarded. Optically the Indian ace was a pawn less but he had dropped it deliberately and could always pick it up anytime.
"It was a very complicated game," said Anand, "I think he missed this manoeuvre in the end that simply wins. Anyways I feel it was more pleasant for me as if white messes up it would be an equal endgame and if black messes up (which happened) he is checkmated," the World Champion added.
As it happened in the game, Shirov's resistance did not last long after Anand got the winning manoeuvre on the board dismantling black's king side in quick time. The game lasted just 26 moves.
Meanwhile in the 'B' group Grandmaster Surya Shekhar Ganguly rose back with a fine win against Friso Nijboer of Holland to take his tally to four points.
The lead positions changed here as Zahar Efimenkov of Ukraine joined Wesley So of Philippines in the lead on 6.5 points.
Tania Sachdev played out a draw with Benjamin Bok of Holland in the 'C' group to take his points to five. Daniele Vocaturo of Italy continued to lead this section with a full point on 7.5 points.