Former midfielder Bastian Schweinsteiger says he was banned from first-team training by manager Jose Mourinho during his time at Manchester United.
Schweinsteiger, 39, made 31 appearances under Louis van Gaal in 2015-16.
He played only four games under Mourinho the following season before joining MLS club Chicago Fire in 2017.
"I was very sad because United was the second club of my heart," Schweinsteiger told the Overlap.
"I gave a lot when I played as well, so that's why I was sad, but I'm not the type of person to go running to the media. It's more important for me to focus on football and behave the way I did."
Former Germany international Schweinsteiger missed the final 11 games of the 2015-16 season because of injury and received treatment in Germany before Euro 2016.
United appointed Mourinho as Van Gaal's successor in May 2016.
Schweinsteiger played six games at the Euros as Germany reached the semi-finals and missed the start of United's pre-season in the USA.
"When I arrived on the first day, I trained with Zlatan Ibrahimovic and thought it was great, a player who has the vision and is amazing to play with," Schweinsteiger said.
"The next day, on my birthday, when I walked into (United's training ground) Carrington, (football director) John Murtough was there and said that I wasn't allowed to walk into the dressing room - the coach had said so.
"I had to ask him to bring me my cleats and training gear. I asked him who I was training with, and he said there was the under-16 team, so I went and trained with the under-16s."
Schweinsteiger's first appearance of that season came in November 2016 in the Carabao Cup against West Ham. He made a further three appearances across the FA Cup and Europa League prior to moving to the MLS.
"The first time someone apologised was when I decided to leave Manchester United for America," Schweinsteiger said.
"I asked Jose if I could do that and he apologised for the way he treated me in the beginning. He had to let me go because he could not do something against me again."
Schweinsteiger retired in 2019 after three seasons with Chicago.
