Daniil Medvedev had just won the biggest title of his career, "the best victory" of his life at the ATP Finals, but did not celebrate.
Instead, he just looked to his box, shrugged, emptied a ball from his pocket, shrugged again before walking expressionless to meet his beaten opponent Dominic Thiem at the net.
And if he wins many more titles, even one of tennis' Grand Slams, he says he will do the same again.
"That is going to be my thing," the 24-year-old Russian said after Sunday's 4-6 7-6 (7-2) 6-4 win in London.
"In tennis I think I probably am the first one, definitely in football I have seen players who do not celebrate.