China is unbeatable in table tennis, and even Chinese officials are worried about the dominance.

China swept all four gold medals again at the London Olympics, duplicating its results from Beijing four years ago.

China men's coach Liu Guoliang, a double gold medalist in 1996, knows the game needs more competition.

"I'd be happy to see the overall standard improve," Liu said. "But of course, I want Chinese players to stay on top. ... But we think others can achieve great success."

Not without China help they can't.

Adham Sharara, president of the International Tennis Table Federation, said he has pushed Chinese officials to open up their sports schools to non-Chinese.

"Their national training center is still closed, but we're trying to convince them to open it," Sharara said. "It's like the US with basketball or Canada with ice hockey. If you keep it only for yourself - you win everything and nobody else can win - then everybody else loses interest.

"China itself has a responsibility to do something, and we have been working a lot with them over the last couple of years."

The ITTF changed the rules after Beijing, allowing only two entries in singles from any one nation. That automatically took two medals from China - it swept all three in men and women's singles in Beijing - but didn't stop the gold haul.

Sharara said he's hoping for more competition in Rio de Janeiro in four years. "It will change in the next four or five years," Sharara said. "You will see other teams will win. Otherwise, of course, it's very disturbing to have the same - whether it's China or the US - winning for too long."

Sharara promised glitz for Rio de Janeiro in 2016. "They want Rio to be different," he said. "We want to add more entertainment there, and what better place than Rio to have some dancers, some music and entertainment between matches."