There were some people who looked at the draw for the 114th edition of the French Open more than a fortnight ago and imagined there was at least a reasonable chance the Swiss national anthem would be played on the final Sunday. But none of them, surely, thought the man gently humming it to himself would be Stan Wawrinka, wearing what looked suspiciously like pyjama shorts, in front of a delirious crowd on a sun-bathed Court Philippe Chatrier. And fewer people will have predicted that the 30-year-old Swiss with the gentle voice and the fiercest single-handed backhand in tennis would humble Novak Djokovic in four sets to become the oldest winner here since Andrés Gómez 25 years ago. This was supposed to be the Serb’s moment, his title, his era. It was the only slam he had not won. Everybody said he would, maybe in three sets. But a city that has always embraced change has a new tennis champion, albeit one with appalling dress sense, who held his nerve long enough at the end of three hours and 12 minutes to beat the best player in the world 4-6, 6-4, 6-3, 6-4. Wawrinka, who now owns two majors, is…