Two-time Olympian Mara Yamauchi expressed her discontent after a transgender athlete beat thousands of women in the women’s London Marathon.

Yamauchi finished sixth in the marathon at the 2008 Beijing Olympics while representing his home country of Great Britain. Yamauchi didn’t mince words when he discussed transgender runner Glenique Frank’s victory in the marathon over the weekend.

«Men in the [female] category is UNFAIR to women,» Yamauchi wrote in a tweet.

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Mara Yamauchi of Great Britain finishes tenth during the 2010 Virgin London Marathon on April 25, 2010 in London, England. (Christopher Lee/Getty Images)

«Nearly 14,000 real women suffered a worse final position [because] him,» Yamauchi wrote on Twitter.

She also noted that during her time as the world’s second-ranked woman that, in her estimate, there were «at least 1,300 men running faster than me.»

Yamauchi also noted that the United Kingdom Athelics applied World Athletics rules on excluding transgender women from elite women’s competitions. She believes this practice made it «fair that athletes who have gone through male puberty are excluded from the female category in track and field.»

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On the other hand, the rules allowed athletes who had already entered events to still run in certain categories, even if it was not their biological sex.

«This man competed under the UK Athletics transition arrangements but it is still wrong and unfair,» Yamauchi told Telegraph Sport.

Mara Yamauchi speaks at an event

Moderator Mara Yamauchi speaks at the event on October 28, 2017 in Frankfurt am Main, Germany. (Ulrich Roth/Getty Images)

Frank previously ran at an event in New York City while wearing a bra and wig.

Frank, who is a British citizen, identifies a woman.

«I branded myself as a woman because I see myself as a woman,» said Frank, who came out a few years ago as Glenique. Frank added that she «since she was five years old she was in the wrong body.»

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Frank, who works as a personal trainer, also noted that the public reaction has been «traumatic.»

Still, «I get it,» Frank said of the criticism. «I feel sad for having upset Mara, because she respects her.»

Mara Yamauch during an elite racing event

Mara Yamauchi of Great Britain, right behind the leaders of the elite women’s race as they pass through Canary Wharf during the Virgin London Marathon 2010 on April 25, 2010 in London, England. (Jed Leicester/Getty Images)

After running the 17th marathon of her career, Frank raved about using «girl power» to help get her through the race.

Some of Frank’s older social media posts feature photos of a man who was married at the time.

During the race last weekend, Frank was elated about becoming a «grandpa» soon.

«So I’m going to be a Grandma, Grandma G!» Frank said in reference to the expectation of becoming a grandfather.

Frank said she was surprised by the pushback given that she wasn’t an elite runner vying for prize money or a podium spot. Instead, she raised the equivalent of $37,000 for charity at the races.

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In the future, Frank plans to enter races «in the ‘other’ or ‘men’ categories.»

«And I still will [the race] in four hours and I won’t steal anyone’s money,» Frank said.