Defending champion Viswanathan Anand's quest to retain the crown suffered a decisive setback after he played out a draw with American Wesley So in the fifth and penultimate round of the Bilbao Masters Final Chess Tournament here.
After suffering a shock defeat at the hands of Dutchman Anish Giri in the previous round, Anand tried hard but could not break the solid defences of Wesley who continues to share the lead along with Giri.
In the other game of the day Giri was held to a draw by liren Ding of China.
With just one round remaining, Giri and Wesley have seven points apiece while Ding and Anand are on four points each under the soccer-like scoring system in place here.
Anand started with the English opening in a must-win situation with white and got the complexities he was looking for in the symmetrical setup employed by Wesley.
The middle game was wild with Anand opting to concentrate on gaining more space while Wesley's knights operated ominously to keep white's advances in check.
Anand castled on the 22nd move and by this time the Filipino-turned American had enough counter play. The Queens got traded on the 29th turn and it was soon a rook and pawns endgame on board. While black had weaknesses it was more of a race in which no one won.
The players promoted a second queen after the rooks got traded, and one more queen each as the game progressed. However, the pawns also subsequently disappeared leading to a draw agreement after 58 moves.
Anand will have black pieces against Ding in the last round game of the Bilbao Masters. A victory can still give him a chance to finish second in this shorter format.
The two leaders clash in the final round to determine the new champion of the Bilbao Masters.