Ian Nepomniachtchi of host Russia became the first player to take the sole lead when he made China's Wang Hao pay the price for a terrible blunder in the fifth round of the Candidates Chess Tournament here on Sunday.
Nepomniachtchi, who had shared the lead overnight with Hao and France's Maxime Vachier-Lagrave, took his tally to 3.5 points.
Second spot
Vachier-Lagrave was in the sole second position with three points. Nine rounds remain.
Hao, who adopted his trusted Petrov's Defence, was comfortably placed until he erred on the 32nd move. He went on to lose a piece, and the game another 11 moves later.
The results (fifth round): Anish Giri (Ned) 2 drew with Fabiano Caruana (US) 2.5; Alexander Grischuk (Rus) 2.5 drew with Ding Liren (Chn) 2; Kirill Alekseenko (Rus) 2 drew with Maxime Vachier-Lagrave (Fra) 3; Ian Nepomniachtchi (Rus) 3.5 bt Wang Hao (Chn) 2.5.
