The Chinese teams are hot favourites to win both finals on Saturday and they were expected to have an easy ride through the preliminary rounds.
Both have qualified for next year's Winter Olympics in Canada, and the women are the current world champions.
But they came to grief yesterday, outplayed by Japan 10-3, while the men lost to Korea 5-4.
The women were beaten by a better team on the day and the men lost because of their safety-first tactics.
Chinese coach Daniel Rafael was disappointed by the women's lack of fight, and by the strategy of the men.
"It was that simple. We didn't show up. Today the broom was not in the right place and the weight was wrong. Nothing was working for us," the Canadian said.
"I could tell by looking at the women's team that their heads were not into the game."
Japan took a four on the third end and led 7-0 after five ends.
The fifth end was disappointing for the Chinese because they had the opportunity to take four but the skip took too much ice.
"Yes we can come back. We've been through it before," Rafael said.
"It was annoying because Japan is a team we will be playing at the Olympics.
"We don't play them every day and when we get the chance we have got to beat them."
The game was called off after the eighth end when Japan took three shots to win comfortably.
In the men's game, Korea drew level with a shot on the seventh end to lock the scores at 4-4, though China had the last rock.
It wanted to keep it for the 10th and last end, because in a tight game the team with the last rock can often dictate the game.
On the eight and ninth ends, China blasted all the rocks out of the house to make sure it held on to the last rock on the 10th end.
It could easily have scored points to get ahead of Korea.
But the tactic came unstuck when Korea successfully put in blocks and skip Kim Chang-Min drew a shot to the red circle then put in a superb block with his last bowl, which made it difficult for China to gain the shot.
Korea is the only unbeaten team in the men's competition, and Japan has lost once and China twice.
The Chinese women came back with a 12-2 win over Korea last night.
• Send us your ski photos and win
