The 21-year-old Smith broke down after docking and took several minutes to calm himself while his upset crew-mates also fought back tears.

With veteran paddling great Clint Robinson on board, Australia's K4 1000m kayak team came a disappointing last in a four-boat semi-final where a top-three place would have given them a back-door entry to tomorrow's final.

"We came here with incredible expectations and to perform like that is quite devastating," Smith said. "The whole Olympic experience has become a disaster.

"The last week and a half (before the Olympics) had been good, and I don't know why we were unable to carry it into the Games.

"There were a few things that started to creep in with the boat. But we have not really talked about it since the race."

Smith said he was confident the crew could perform, but it had failed to do so.

"I don't know the answer why," he said.

In his Olympic swansong, Robinson must today produce a major boilover with a top-three finish in the K2 500m semi-final with rookie Jake Clear to continue his fading dreams of a fifth and final medal.

The 36-year-old, who lambasted the crew's heat shocker on Monday, was too distraught to speak after the race where the faltering Australians were tipped out of third by 0.171 seconds by Canada.

With a mere 10 boats in the event, the crew of Robinson, Smith, Tate Smith and Tony Schumacher were embarrassingly the only team to miss a position in the final.

In one of the shortest mixed zone interviews ever, Robinson said he wasn't sure what went wrong with a boat that came to Beijing expecting to contest the medals.

Asked if he was devastated, Robinson said: "Wouldn't you be? There's nothing more to say guys.

"We'll talk about it as a group. The conversation's not for here and now."

Although Australia's heat performance was rated a disaster by a seething Robinson on Monday, Canada's time in their heat was six seconds slower than Australia and they stunned all by making it up today.