In an interview on the italian Corriere della Sera, Ans Botha, the 75 years old coach of Wayde Van Niekerk, said that 12 days before Rio, in a day-workout he run 3 times 9"9 over 100 mt, and than twice 14"7 over 150 in the same.
She remained shocked and she told to the newspaper that in that moment had known that Wayde would win the gold medal in Rio.
(the interview in Italian)