Rafael da Silva has claimed that Louis van Gaal did not like him and wondered if the Manchester United manager has a problem with the Brazilians.
Rafael's seven-year stay at Old Trafford ended last week when he joined Lyon for €3 million.
The right-back had been a regular under previous managers Sir Alex Ferguson and David Moyes but began just six league games under Van Gaal, the last of them in October.
Van Gaal has had a difficult relationship with some Brazilians at previous clubs, including Rivaldo and Giovanni at Barcelona, and Lucio, whom he sold when he was Bayern Munich manager.
And Rafael told Globo Esporte: "I know this history that he doesn't like Brazilians, but I can't say: 'Oh, he doesn't like Brazilians.'
"I know that he didn't like me, but if that's because I'm Brazilian, I don't know."
Van Gaal also let Anderson leave United, although the Brazilian midfielder had fallen out of favour long before his appointment.
Rafael said he felt Ferguson's 2013 retirement was a "fatal" setback for his United career and felt that the Scot's final year was his best at the club.
"I did the complete season, when he [Ferguson] left," he added. "In 2012-13 I played almost every game, it was my best season at United, we were even champions.
"And that's when they changed the manager. That change was fatal for me. I was going well, then Ferguson left."
Rafael, who was reluctant to discuss Moyes, said he was disappointed when Van Gaal preferred to use winger Antonio Valencia at right-back.
"I won't talk much about the relationship with Moyes, because it was too little, less than a year," he said.
"Valencia started playing as a right-back for Van Gaal. He's also a great player, but I was doing well in that position.
And he revealed that Ferguson got in touch to send his best wishes now that he has moved to Lyon.
"Ferguson even called to wish me good luck," he added. I had a very good relationship with him, he helped me a lot in Manchester, and always did everything to help me. He signed me when I was 16, I don't even know what to say."