Shakhriyar Mamedyarov of Azerbaijan has moved up to joint leadership of the FIDE Candidates Tournament as it approaches the halfway point in Berlin ©Getty Images

Fabiano Caruana of the United States has been joined in the lead on four points by Azerbaijan's Shakhriyar Mamedyarov as the World Chess Federation Candidates Tournament 2018 approaches its halfway point.

Caruana drew with Russia's Alexander Grischuk today in the sixth of the 14 scheduled rounds that will produce a single challenger for defending champion Magnus Carlsen in the World Chess Championship that will take place in London later this year.

Mamedyarov, world ranked number two, bridged the gap with victory over the early pacesetter, Russia's wildcard Vladimir Kramnik, who is now third overall with three points.

Also on three points is Grischuk and China's Ding Liren, who drew today against Russia's Sergey Karjakin at the Kuehlhaus venue in the German capital Berlin.

Russia's Sergey Karjakin, who lost the last world title match against Norway's Magnus Carlsen on a tie-break, has yet to win as the FIDE Candidates Tournament approaches its halfway point ©Getty Images
Russia's Sergey Karjakin, who lost the last world title match against Norway's Magnus Carlsen on a tie-break, has yet to win as the FIDE Candidates Tournament approaches its halfway point ©Getty Images

The 28-year-old Karjkin, who lost the last world final to Carlsen on a tie break, has still to win in this tournament and is currently the lowest ranked of the eight challengers with two points.

In the last of today’s matches, Wesley So of the United States earned his first win of the event against Levon Aronian of Armenia.

In the next matches on Sunday (March 18), Mamedyarov faces Grischuk and Caruana meets Aronian.

The event, due to last until March 28, is being contested as a double round-robin with each player playing 14 games, seven with white pieces and seven with black.

A top prize of €95,000 ($117,000/£85,000) is on offer for the winner.