By Nick Mulvenney

RIO DE JANEIRO (Reuters) - World champion Dafne Schippers shook off injury to reach the 200 meters semi-finals but twice Olympic gold medalist Veronica Campbell-Brown made an early exit from her fifth Games on Monday.

Campbell-Brown, back-to-back champion in 2004 and 2008, finished third in the ninth heat and her time of 22.97 was not enough to get through to Friday's semis.

The 34-year-old, who will also run in the 4x100 relay, blamed poor execution but did not rule out returning for a sixth Games in Tokyo in 2020.

"I've been through worse in my life," she said. "This is not such a crazy hurt to get over, I've never been in this position before. I don't know why things happen but sometimes you don't get your desire."

Trinidad and Tobago's Michelle-Lee Ahye, sixth in the 100, ran the fourth fastest time of a sunny morning to win heat three in 22.50, one-hundredth of a second ahead of Schippers who won heat one.

With champion Allyson Felix unable to defend her title after failing to finish in the top three at the U.S. Trials, Dutchwoman Schippers came to Brazil with high hopes of adding the Olympic title to the world title she won last year.

A leg muscle injury prevented her from running freely as she finished fifth in the 100 meters on Sunday but she said at one stage it looked like she would not compete at all in Rio.

VERY DISAPPOINTED

"Last Wednesday I was ready to go home because of the injury," she explained.

"But I carried on. All I could do was to run and have treatment. I was very disappointed that I wasn't able to show what I'm capable of doing.

"I was broken. I didn't come here to finish fifth but that was the maximum I could do," said Schippers.

The 24-year-old said she was feeling "better" on Monday after winning her heat easing up.

"I'm glad it went so well in the 200," she added. "I've now got the chance to show what I am capable of doing."

Elaine Thompson proved on Saturday that the Jamaican sprint production line is still going strong and the 100 meters champion progressed in 22.63.

She had to settle for second place in heat four behind Ivorian Marie-Josee Ta Lou though.

African champion Ta Lou missed out on a bronze medal in the 100 by a few thousandths of a second and looked like she had a point to prove back on the blue track of the Olympic Stadium as she topped the timesheets with a personal best 22.31.

Just behind her were two Americans in Deajah Stevens (22.45) and Tori Bowie who backed up her silver medal in the 100 by winning her heat in 22.47.

(Editing by Tony Jimenez)