They were told the fantastic news yesterday morning by the International Tennis Federation.
The twins claimed a spot in the doubles draw because they were the first alternate and replace Federer and Stan Wawrinka in the 32-team competition which starts on Saturday.
A knee injury will sideline Federer for the rest of the year.
It will be the first time Thailand has competed in men’s doubles at the Olympics. Tamarine Tanasugarn, Pardorn Srichaphan and Tamarine and Benjamas Sangaram played women’s singles (1996, 2000, 2004 and 2008), men’s singles (2000 and 2004) and women’s doubles (1996 and 2000) at the Games respectively.
“I watched the Olympics on TV in 1992 and dreamed that one day I could compete for the country there,” Sonchat, the older of the brothers, said.
“This is by far the greatest tournament in my career. Although I have played 16 Grand Slams, the Olympics is the most important in my view and I wanted to be part of it since I was a boy.”
The siblings just missed out on playing at the 2008 Beijing Olympics when they were ranked No 62 in the world. They had given up hope of being selected for Rio given they are now ranked outside the top 100. “We were informed a few days ago to be on standby and it was just confirmed this morning [Saturday],” Sanchai said. “Our flight is on Monday. Ready or not, we are absolutely going there.” Thailand will be represented in Rio by 34 athletes in 17 sports.