By Alexandra Ulmer

RIO DE JANEIRO (Reuters) - After a disappointing routine at the uneven bars women's final on Sunday, U.S. gymnast Gabby Douglas said she was upset by "negative" online comments attacking her appearance, patriotism and support for team mates.

Douglas, 20, has sparkled as part of the winning all-star U.S. women's team in Rio - but social media attacks have been so vicious they have ruined her Olympic adventure, Douglas' mother told Reuters.

The London 2012 all-around gold medalist, Douglas failed to qualify for the competition in Rio and her Sunday routine on the uneven bars - long her strong suit - was marked by hesitations that pushed her down to the second-to-last place.

"There's been a lot of negativity, it's just been a little bit hard and at the same time very upsetting," Douglas told reporters in Rio about the online attacks.

"When I would read those comments it was just like, "What? Really?"

Douglas has been targeted over her hair, a perceived lack of patriotism for not placing her hand over her heart as the U.S. anthem was played during a medal ceremony, and for not joining a standing ovation for team mates Simone Biles and Aly Raisman.

It is not the first time she has been attacked.

In 2012 Twitter went into overdrive after she became the first African-American gymnast to win the Olympic all-around title. But rather than lauding her excellence, critics rounded on her for the state of her hair during the final.

Douglas is fed up, her mother Natalie Hawkins said.

"What was going through her head was 'I'm being attacked for everything I do so I might as well not do anything. Because no matter what I do, I am being attacked'," said Hawkins, who said her daughter was being called "Crabby Gabby."

While Hawkins said many people had told her the attacks were racially motivated, she said she wanted to "have more faith."

Her daughter too, said she was remaining upbeat about her experience at the first South American Olympics.

"I tried to stay in my own little bubble," said Douglas, who has almost a million followers on Twitter and starred in her own reality TV show.

"I'm just going to leave here with a good, positive note."

(Reporting by Alexandra Ulmer, editing by Neil Robinson)