There were no shortage of theories about what was going through Michael Phelps' mind when he delivered one of the lasting images of the Rio Olympic Games.
Prior to his 200m butterfly semi-final, Phelps was caught by cameras staring a hole through South African rival Chad Le Clos, who beat Phelps to win the gold in the event four years earlier in London.
Le Clos, who had been sitting next to the American, stood in front of him and began shadow boxing, which many thought disturbed his rival's mental preparation.
Others thought he may have been possessed.
Whatever the case, Phelps did not look impressed, and Twitter exploded.