By Brian Oliver

RIO DE JANEIRO (Reuters) - Russia’s Olympic ban and China’s ruthless selection policy helped pave the way for Thailand's Sopita Tanasan win the first weightlifting gold medal of the Rio Games in the women’s 48kg on Saturday.

Tanasan, daughter of an international boxer, became Thailand’s fourth gold medalist in women’s weightlifting with a total of 200kg.

China had the favorite for the contest in Hou Zhihui, who lifted 210kg in her national championships in April, but, being allowed to enter only four lifter overall, sent her home from their pre-Games training camp in Sao Paulo last week when they decided they had a better chance in the heaviest category, +75kg.

Hou injured her knee in July but thought she had recovered enough to compete. Wang Guoxin, head coach of China’s women’s team, opted instead to send for Meng Suping. He said the decision was influenced by Russia’s ban from Rio for “bringing the sport into disrepute” with their doping record.

Once that ban was confirmed last week it meant the hot favorite in the +75kg, Tatiana Kashirina, would not compete.

"Yes, Kashirina's absence did give us a big opportunity to win in that division, because only Meng and Kashirina have the ability to lift over 300kg in total,” said Wang. Meng arrived in Rio today on Saturday.

Tanasan, 21, won by 8kg from Indonesia’s Sri Wahyuni Agustiani. In third place was Japan’s Hiromi Miyake, the 2012 silver medalist who was competing in her fourth Games.

"When asked if she would try for a fifth time in her home country at Tokyo 2020 she said, “I want to enjoy this medal now and I will think about that when I return home."

Another of Sopatan’s strongest rivals, Vietnam’s Thi Huyen Vuong, failed to register a total after three failures in the snatch.

Margarita Yelisseyeva, of Kazakhstan, who finished fifth, had plenty of support in the crowd at the Riocentro arena but not behind the scenes within the sport.

The International Weightlifting Federation voted in June to ban Kazakhstan and Belarus from the Games, along with Russia, because of their positive doping cases in retested samples from 2008 and 2012.

The ban was subject to the International Olympic Committee completing the legal processing of those tests before the entry deadline, and that did not happen. Both nations have teams of eight lifters in Rio, while Russia was excluded on evidence from the McLaren Report into state-sponsored doping.

(Editing by Bill Rigby)