However, he failed to establish himself in the first team, and turned down the chance to extend his stay at the club to join FC Heidenheim in 2018.
Dropping down in the second division provided him with the opportunity to get regular games. He is playing with confidence now, and has established himself as a regular member of the side.
The youngster has scored one goal and provided two assists in 11 appearances in the second tier of the German league.
Neil Lennon has recently suggested that Celtic will be active in the January transfer window, and the Bhoys will be looking to bring in some quality players.
The midfield is one area where Lennon can add depth and quality. Dorsch could be a long-term replacement of Scott Brown who is approaching the fag end of his career.
Celtic have made some very good signings this summer and credit must go to the scouting team for bringing to notice some quality players. The youngster is technically gifted and could turn out to be a gem of a signing for the club.