Fabiano Caruana took the lead after the fourth round of matches as he beat Russian wild card Vladimir Kramnik at the World Chess Federation (FIDE) Candidates Tournament 2018 in Berlin.
The American player has a half-point lead over Kramnik following his win over his Russian opponent at the Kuehlhaus venue in the German capital.
Caruana sits on three points, 0.5 in front of Kramnik and Azerbaijan's world number two Shakhriyar Mamedyarov.
Mamedyarov halved his fourth round contest with Filipino-American Wesley So today.
Standings after round 4:— Berlin Candidates 2018 (@FIDECandidates) March 14, 2018
1 Caruana 3
2-3 Kramnik, Mamedyarov 2.5
4-6 Aronian, Grischuk, Ding Liren 2
7-8 Karjakin, So 1#BerlinCandidates
Caruana will be hoping to continue his superb start to the tournament, the winner of which will go on to face Norway’s 27-year-old Magnus Carlsen for the world title, when he tackles Russian Sergey Karjakin tomorrow.
Karjakin, who lost to Carlsen on a tie-break in the last World Championship final two years ago, endured another difficult outing as he was beaten by Armenia's Levon Aronian.
The tournament, 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 also on offer for the winner.