There have been some ugly moments which have made spectators wince at the Olympics this week.
Germany's Beijing Olympic champion Matthias Steiner pulled out of the men's super heavyweight weightlifting final overnight after receiving a blow to the head from the falling bar when his arms buckled under a 196kg snatch lift.
Steiner left the stage on his feet, raising a hand to acknowledge the cheers of the crowd but subsequently was withdrawn at the end of the snatch lift round.
Meanwhile, the sound of thwacks resonated around the Olympic diving pool on Monday night.
The dramatic flops and mighty splashes during the men's three-meter springboard heats were capped by the unexpected sight of world champion and runaway gold medal favorite Qin Kai stepping off the board wrong, over rotating and entering the water on the diagonal.
Qin, who won the synchro gold medal five days ago, scored just 39.90 for the dive, less than half he would normally expect, but did enough on his other dives to ensure he qualified in 11th position.
Qin was not the only one to struggle.
Russia's Evgeny Kuznetsov, silver medalist in the synchro, seemed to have sunk his hopes after he made a whale-like splash on his third dive, but also managed to just get through in 16th place, with 18 of the 30 divers qualifying for the semi-finals.
Venezuela's Edickson Contreras, however, did not have the same luck and he was left in tears after he took off wrong on the fourth dive and then made a mess of a nervy final dive, retaking the run-up and flopping into the pool.
Germany's Stephan Feck also had bad luck and had to withdraw after he failed his second dive, appearing to hurt his leg and hit the water flat on his back.
He climbed out of the pool after huge gasps from the crowd, and received zeroes from all the judges.
Then Britain's Jack Laugher had a 'knee buckle' on his final dive and his legs gave way, leaving him crashing to the pool with a puzzled look on his face.
Earlier this week, the favourite to win gold - America's McKayla Maroney - missed out on the medal after landing on her rear during her second attempt in the women's vault finals, following an almost flawless first attempt.
The 16-year-old appeared to land on her heels and then her legs skidded out from under her as a look of shock registered on her face.
Maroney claimed the silver medal and looked less than impressed as she received her medal.