World Champion Viswanathan Anand had to settle for a draw against Sergey Karjakin of Russia in the first round of the Tal Memorial Chess tournament in Moscow.
After a forgettable show in the just-concluded Bilbao final masters, Anand could do little against the solid defences of his younger rival and drew the game in 42 moves.
The shock of the day was recorded by Ian Nepomniachtchi of Russia who defeated compatriot Vladimir Kramnik in the opener.
In the other decisive game of the day, Vassily Ivanchuk of Ukraine got the better of World Cup winner Peter Svidler of Russia.
The strongest ever tournament in terms of ELO rating saw draws on the remaining two boards as Hikaru Nakamura of United States signed peace with Boris Gelfand of Israel, while Levon Aronian achieved the same result against World number one Magnus Carlsen of Norway.
With eight rounds still to go in the 10-player round-robin tournament, Ivanchuk and Nepomniachtchi emerged as the early leaders while Anand, Carlsen, Gelfand, Nakamura, Aronian and Karjakin follow them a half point behind. Kramnik and Svidler are at the bottom of the tables.
For Anand, the Capablanca variation in the Nimzo Indian defence gave a semblance of an advantage but it was never enough.
Karjakin, who is known for deep opening preparation went for the trading of a few minor pieces in the opening and once the queens were off the board there was not much to look forward to.
Anand gave up a pawn on king side to get an outside passed pawn on the other flank but Karjakin traded the knights at the right juncture to neutralise. The draw was a just result.
Kramnik suffered a rare loss with his white pieces in an English opening game. The former world champion came under pressure in the middle game when Nepomniachtchi forced a favourable exchange of queens and reached an endgame with better prospects.
Kramnik could only watch in dismay as Nepomniachtchi got two passed pawns in the opposite coloured Bishops endgame that ensued and went down in 53 moves.
Ivanchuk displayed immaculate technique in demolishing Svidler. The Grunfeld defence was tackled by the Ukrianian with a relatively less played system and after the dust subsided the extra pawn played its part to perfection.
Ivanchuk won in 61 moves.
Aronian drew with Carlsen after 57 moves of a Queen's Indian defence while Nakamura could not impress Gelfand in a Queen's gambit declined and drew in 34 moves.
Results of round 1: Vishwanathan Anand (IND) drew with Sergey Karjakin (RUS); Vladimir Kramnik (RUS) lost to Ian Nepomniachtchi (RUS); Hikaru Nakamura (USA) drew with Boris Gelfand (USA): Vassily Ivanchuk (UKR) beat Peter Svidler (RUS); Levon Aronian (ARM) drew with Magnus Carlsen (NOR).