By Brenda Goh

SHANGHAI (Reuters) - For former Chinese athletes that now compete for other countries' flags, an Olympic meeting with the Motherland at Rio de Janeiro will be bittersweet.

Scores of China-born athletes have switched citizenship in the two decades since the Asian powerhouse returned to the Olympic fold in 1984, driven by stiff competition for national team places that has shut out many aspiring Olympians.

The Chinese emigres are most apparent in the table tennis tournament at Rio, where China is expected to dominate as usual.

Discounting 12 players competing for China, Hong Kong and self-ruled Taiwan, 27 of the 140 entrants in the singles were born in China but will represent nations like Portugal, Qatar and Republic of Congo.

"The first feeling if I meet them (in competition) is that I'm very unlucky, because it's very difficult to beat them and it feels like the match may be over very quickly," Melek Hu, who will represent Turkey in her second Olympics after moving there about a decade ago, told Reuters in a phone interview.

"But the Chinese team represents the highest level of competition, one also wants to see how wide the gap is between them and I. After all, you won't always get a chance to exchange blows with such high standards."

China has won 24 out of 28 gold medals since table tennis became an Olympic sport in 1988 and is known for its cutthroat selection and military training drills.

In 2012, the game's rules were changed to allow each country to only enter two players into the singles events, preventing one country from winning all the medals as China did at the 2008 Beijing Games.

Japan, North Korea and South Korea are among teams expected to put up a tough fight against the Chinese in Rio, along with Singapore who will field a women's team of China-born players.

Hu, a 27-year-old from China's northeastern Liaoning province, said she moved abroad after feeling she was getting too old to qualify for the national team, which made her contemplate giving up the sport.

"Of course every table tennis athlete in China has a dream of entering the national squad," she said. "So with the pressures of having to decide whether I should find a job or do something else, I chose to go overseas to play and train."

Her path is similar to that of Beijing-born Wu Yue, who will compete for the United States at her first Olympics after obtaining her green card in 2014.

Wu, who also goes by her English name Jennifer, said life in China as a table tennis professional is easier because of the considerable amount of government support given to athletes.

But she said her freedom to choose her own schedule and competitions had been invaluable.

"There are too many talents in China. In China I didn't count as a talent," she told Reuters.

"I feel that it doesn't matter which country you're playing for, this fulfils my Olympic dream ... It means that I didn't play table tennis for nothing."

(Editing by Ian Ransom)