By Mary Milliken

RIO DE JANEIRO (Reuters) - For American gymnast Aly Raisman, a silver medal in Thursday's all-around event was a moment of redemption after the heartbreak of 2012 when she was on the wrong side of a tiebreak and bumped from the podium.

It was also a validation that a 22-year-old can still rock in the world of gymnastics, despite an army of naysayers who didn't think she could compete in a sport made for teens.

Raisman rose to the podium alongside compatriot and gold medal winner Simone Biles and bronze medalist Aliya Mustafina, the Russian rival that had prevailed in the tiebreak for the bronze in London.

"After the tiebreak of 2012, it was very heartbreaking," said Raisman.

But Thursday's silver, she said, "shows you should never let anyone tell you that you can't do anything, and you should never give up just because you fail in something."

In 2012, Mustafina and Raisman finished with the same total score and the tie was broken by using their three highest apparatus scores. Mustafina came out a hair higher, leaving Raisman in fourth.

Raisman said she had to stare down the skeptics when she came back too the national team in 2014 after a series of injuries.

"When I first came back, all the media and everyone looked at me like I was crazy that I was really going to come back," said Raisman.

Her coach, Mihai Brestyan, told her "'just said ignore everyone,'" she said. "'When you are 21 or 22, that will be your best age.' And he was right."

But at the 2015 world championships, she finished a disappointing fifth.

"I wouldn't call fifth in the world a failure," she said.

"But sometimes when you make mistakes," she added, "it's the best thing for you."

After their one-two finish Thursday, Raisman and Biles, 19, walked around the Rio Olympic Arena, as if they were one. The two are very close and Raisman said "the whole time we have been here together, that's been our goal to go one-two."

Biles, who many call the best gymnast of all time, was ebullient about her team mate's accomplishment.

"I was more proud for Aly getting silver than me gold," Biles said. "She just worked so hard in gym and for it to finally pay off, it amazes me."

Raisman returned the compliment by saying that she never thought she could beat Biles.

"No one goes in thinking they can beat Simone," Raisman said. "People don't go in thinking they can beat Usain Bolt either. It's kind of the same thing."

The two plan to take a beach vacation in Belize, the homeland of Biles' mother Nellie, and ponder their futures.

"I feel really good at 22 and I can't wait to see what is to come," Raisman said.

Biles chirped "2020?," hoping her friend will be coming along for the Olympic Games in Tokyo in 2020.

(Additional reporting by Drazen Jorgic; Editing by Pritha Sarkar and Frank Pingue)