The centre-back has revealed how he struggled to win the trust of the Rojiblancos during his spell in the Spanish capital, and relished being able to prove his worth in Germany
The double Europa League winner broke into the Atleti first team in 2008 after seven years in the club's cantera, but left for Bundesliga outfit Borussia Monchengladbach this summer in a deal reportedly worth €8 million.
"My old club never bet much on homegrown talent," Dominguez lashed out on Radio Marca.
"Every year, they brought in a new centre-back to compete with me for a spot. I've never been afraid, but I felt it was time for a change this year."
In Monchengladbach, Dominguez will have the opportunity to work under Lucien Favre, who has a reputation for helping young players break into their respective national teams.
The 23-year-old is expected to play a part for Spain at the London Olympics this summer.