Mustafa Kapi made his debut as the youngest Galatasaray player in the club's history with his Süper Lig debut at the end of the first half. The 4-2 victory of defending champions Galatasaray over Demir Grup Sivasspor on the 17th matchday of the Turkish league young star Mustafa Kapi make his debut at the age of 16, four months and 15 days for the Yellow Reds. Kapi thus replaced the previous record holder Emre Belözoglu (16 years, eight months, ten days) as the youngest player in the club's history in the Süper Lig. Belözoglu has held this record since the 1996/97 season, when he celebrated his first league appearance against MKE Ankaragücü on the 33rd matchday of the Süper Lig.

Kapi has played 25 junior internationals for the Turkish U14, U15 and U16 (two goals) and is currently in the U17 squad. The Denizli-born midfielder still has a contract with Galatasaray until 2020, and Kapi has also played five UEFA Youth League campaigns this season. He was on the pitch for 324 minutes and scored one goal.