Ilkay Gundogan has revealed why he rejected the chance to reunite with Jurgen Klopp at Liverpool to join Manchester City in the summer of 2016.
The German midfielder joined Klopp at Borussia Dortmund in May 2011 and enjoyed some of the best years of his career.
Under the now Liverpool manager's leadership, Gundogan lifted the Bundesliga title and German cup as well as helping his side reach the final of the Champions League.
Following Klopp's move to Anfield to replace Brendan Rodgers, he was eager to link up with Gundogan again and attempted to bring him to Merseyside. However, Gundogan moved to City instead, becoming the first signing of the Pep Guardiola era.
The 29-year-old revealed he rejected the advances of his former boss in search of a new challenge.
"I believe in challenges in life and I always try to challenge myself first of all," he said during an interview with FantasyPL.
"I feel like if I don't challenge myself and get out of my comfort zone, I'm not going to change anything and won't improve.
"So I had a great four years with Jurgen and I love him as a person and a manager but I felt it was time for something else.
"I wanted to leave Dortmund in Dortmund and didn't want to think about the time that I had with him when I was joining a new club.
"That was a bit of the reason why I didn't want to join Liverpool."
Gundogan also revealed the chance to work with Guardiola was a major factor in moving to the Etihad Stadium as he had dreamt of working with the Catalan.
He added: "Obviously, on the other side there was Pep Guardiola who I loved watching when he was at Barcelona - the way he made his team play.
"When he was with Bayern Munich, I played against him and you felt on the pitch how strong his sides were and it was always a dream to call him my manager one day.
"At that point, I had the possibility to train and play for him and the combination with Man City was perfect.
"I just thought okay that's the next step for me and the next challenge.
"Even though the start was not so easy, I think I've made the right decision and I'm very happy here."