NOT for the first time this year, world champion Magnus Carlsen, the sport’s dominant player for the last decade, has rocked the chess world, this time withdrawing from a prestigious — and highly lucrative — invitational tournament in the US implying that his opponent, Hans Niemann, had been cheating.

Having already withdrawn from next year’s world title match, Carlsen pulled out of the 10-player round-robin Sinquefield Cup, held in St Louis, Missouri, after an unexpected third-round defeat as white to the 19-year-old Californian grandmaster last Sunday, simply tweeting a clip of football coach Jose Mourinho’s unsubtle complaint about refereeing: “If I speak I am in big trouble.” 

The 31-year-old Norwegian’s message was that he had been diddled, and for the past week the experts have been poring over the game, trying to divine whether Niemann had some sort of help with his moves as the pair faced off over the board — and how it might have been achieved.