The 29-year-old Nepomniachtchi (known as ‘Nepo’ by fans) played his moves in double-quick time to beat China’s Ding Liren in dramatic fashion in round 6 of the Candidates Tournament, opening up a full 1-point lead at 4.5/6 over his nearest rival, Maxime Vachier-Lagrave of France. If Nepo can retain his lead and win the event, he will challenge Norwegian world champion Magnus Carlsen for his title in December in Dubai.

Yet worries surfaced that Nepo, a renowned speed specialist who is one of only a few players in the world to enjoy a plus score against Carlsen, may have contracted coronavirus after he coughed incessantly through a post-game press conference.

New World Chess Federation (FIDE) health rules, brought in specially for the 8-player Candidates Tournament in Ekaterinburg, stipulate that if any player tests positive for coronavirus, the entire event will have to be postponed for several months – with players resuming with their scores when the tournament was halted.

Nepo’s health scare came despite showing some of the best form of his life in the first six games of the 14-round, double round robin tournament. He has defeated both Chinese challengers (Ding Liren and Wang Hao), along with the Netherlands’ Anish Giri in Round 1, and drawn with American top seed Fabiano Caruana, and his Russian compatriots, Aleksandr Grischuk and Kirill Alekseenko.

Nepo’s win over Ding, the number 2 seed tipped before the tournament as a potential challenger to Carlsen, came after the Russian grabbed a clear advantage with a passed pawn that threatened to become a queen, and then survived a dangerous counter-attack that put his own king in jeopardy. At one point, the out-of-form Ding missed a brilliant combination that would have either forced a draw by perpetual check, or even checkmated Nepo sensationally if the Russian had pressed for the win.