"Borussia is my first love and it will be always like this", assured Ter Stegen, 24 years old, who joined FC Barcelona in 2014.
"It was very emotional when I left the club. I face Gladbach sooner than I thought and I am very impatient", he told the reporters.
"I had a very good time here and I've played my whole career here except the last two seasons but Barcelona was one of the random clubs I couldn't turn down. I am sure the Borussia fans can understand my decision", he added.
Despite the missing of Lionel Messi, who is injured, Barcelona is the favourite for tonight's game after their 7-0 victory against Celtic Glasgow.
Monchengladbach lost the last time 4-0 against Manchester City.