Outside of Greece, Karelis has appeared in other major European countries, including stints with Genk (Belgian Jupiler Pro League), ADO Den Haag (Dutch Eredivisie), Brentford (English Championship) and Amkar Perm (Russian Premier League).

The 32-year-old has also made his mark in the UEFA Europa League group stage, featuring for both Panathinaikos and Genk and scoring four goals in 12 appearances. Throughout his club career, spanning 361 games, Karelis has been known for his all-round game and contribution in the final third, with 103 goals and 29 assists.

Before becoming part of the senior Greece team, Karelis played and scored regularly for the national youth teams, scoring 15 goals in 43 appearances. On his full international debut with the senior team, he scored against Finland in Helsinki during the UEFA Euro 2016 Qualifiers. He represented his country in 19 matches and scored three goals.

Karelis will look to bring his leadership, distinctive playing style and wealth of experience to bear as he looks to contribute to Mumbai City's ambitions for the upcoming season.

"I am delighted to embark on this new journey in a culturally rich country. I have heard many wonderful things about Mumbai City FC and I cannot wait to join the club. The team has achieved significant success in recent years and I am eager to contribute to their continued success in the upcoming season. I look forward to being a part of this dynamic team and playing in front of their passionate fans," Karelis said in a statement.

Mumbai City FC coach Petr Kratky said: "Nikos is a highly talented player who perfectly meets the requirements we expect from our forwards. He has experience playing in several European countries and has consistently demonstrated his caliber in different leagues. We are confident "We are extremely excited about his abilities and we are excited to have him join us for next season. We believe his skills and experience will be valuable to our team."