By Pritha Sarkar

RIO DE JANEIRO (Reuters) - Dethroning champions China is the number one target for Japan at the Rio Olympics but after a day of falls and botched landings in men's qualifying on Saturday, Kohei Uchimura and his team mates were left with sore bodies and bruised egos.

Uchimura suffered the most spectacular of falls from the horizontal bar -- an apparatus on which he is the world champion -- as he lost his grip following a release-and-catch maneuver and landed on his back with a thud.

The glaring errors on every apparatus barring the floor exercise by the reigning Japanese world champions meant their total of 269.294 was surpassed by China (270.461), the United States (270.405) and Russia (269.612).

London Games bronze medalists Britain, jubilant hosts Brazil -- who were fielding a full team in the men's Olympic competition for the first time -- Ukraine and Germany also qualified for Monday's team final.

Japan's woes were put in context when Frenchman Samir Ait Said and German gymnast Andreas Toba provided a painful reminder of just how dangerous gymnastics can be.

Ait Said suffered a broken leg that was left dangling from below his knee following a crash landing from the vault and had to be taken out of the arena on a stretcher.

Toba may have suffered an injury to his anterior cruciate ligament following a fall from a tumbling run on the floor exercise. Incredibly he went on to perform on the pommel horse but as he limped off that apparatus, with his arms around his team mates, it was clear his Rio adventure was over.

"I cried like a little kid," Toba told reporters. "The injury on my knee is big, but the emotional injury is way bigger. A first diagnosis said it is the ACL."

While Japan lived to fight another day, Uchimura lost his chance to be in the running for the horizontal bar gold as his score of 14.300 left him well outside the top eight scores needed to reach the apparatus final.

That mishap did not stop him from reaching the all around final, where he will be bidding to become the first gymnast since compatriot Sawao Kato in 1972 to win successive Olympic titles in the event that tests skills across six apparatus.

Japan can now forget about Saturday's horror show since none of the scores will be carried through to Monday's team final but they cannot afford a repeat performance if they want to end China's eight-year reign as Olympic champions.

"What happened today can only make me stronger," Uchimura, who finished second in the all around standings behind Ukrainian Oleg Verniaiev and also made the cut for the floor final, told reporters.

"I need to repress my feelings so I can perform better at the next competition."

While in qualifying four competitors from each country compete on each apparatus with only the top three scores counting toward the total, in the final each nation will put forward three athletes and all three scores will count.

Since 1994, Chinese men have won 10 of 12 world championship team titles and three of the last four Olympic golds on offer.

The team that were toppled from their perch by Japan at last year's world championships will be eager to prove on Monday that they have recovered from their bronze medal finish in Glasgow.

(Additional reporting by Liana Baker; Editing by Toby Davis, Tom Brown and Peter Rutherford)