Galatasaray dropped out of the title race after being held to a 1-1 draw against Basaksehir at the Fatih Terim stadium.
The home side took the lead on 51 minutes when Danijel Aleksic finished off a clever move.
Başakşehir 1-0 Galatasaray
İrfan Can'dan asist. 🔥🔥
— @goalforza'yı takip ediniz. (@canligol_tv) June 28, 2020
The Lions did equalise when Emre Akbaba found the back of the net on 67 minutes.
Basaksehir had a nervy end to the game after Edin Visca was sent off with five minutes left – his first ever red card – but the reigning champions were unable to capitalize on their man advantage.
The draw saw Galatasaray fall eight points behind league leaders Basaksehir.
The Yellow-Reds are currently 4th in the league and are now just two points ahead of 5th placed Besiktas.
The Istanbul giants have yet to win a game since returning to action following the coronavirus disruptions.
Galatasaray still have all to play for as Trabzonspor are suspended from European competition next season.
The Lions face 2nd placed Trabzonspor next week and could close the points gap to just three points with a victory.
Basaksehir meanwhile, are two points ahead of Trabzonspor and would lift the league title for the first time should they clinch the championship.
The Istanbul minnows would become the seventh separate side to be crowned champions if they do win the Super Lig.