Pausanias Description of Greece 5.9.3

[3]
  The order of the games in our own day, which places the sacrifices to the god for the pentathlum and chariot-races second, and those for the other competitions first, was fixed at the seventy-seventh Festival. Previously the contests for men and for horses were held on the same day. But at the Festival I mentioned the pancratiasts prolonged their contests till night-fall, because they were not summoned to the arena soon enough. The cause of the delay was partly the chariot-race, but still more the pentathlum. Callias of Athens was champion of the pancratiasts on this occasion, but never afterwards was the pancratium to be interfered with by the pentathlum or the chariots.

[3] The order of the Games in our own day, which places the sacrifices to the god for the pentathlon and chariot races second and those for the other competitions first, was fixed at the seventy-seventh Festival. Previously, the contests for men and for horses were held on the same day. But at the Festival, I mentioned the contestants in the pankration prolonged their contests till nightfall, because they were not summoned to the arena soon enough. The cause of the delay was partly the chariot race but still more the pentathlon. Kallias of Athens was champion of the pankration on this occasion, but never afterwards was the pankration to be interfered with by the pentathlon or the chariots.