Basaksehir were held to a goalless draw away to Sivasspor at the 4 Eylul Stadium in the Super Lig on Sunday.
The league leaders struggled to create chances over the course of the 90 minutes and were fortunate not to concede on the counter attack.
Sivasspor had several chances to take the lead but were unable to convert.
The league leaders have now dropped points in five of their last six games.
The Istanbul minnows have now dropped points in their last four games and are now just three points ahead of 2nd placed Galatasaray and four behind 3rd placed Besiktas.
Galatasaray host Besiktas at the Turk Telekom Arena next on Sunday in the Istanbul derby.
Besiktas will close the gap with the league leaders to just one point with a win over the reigning champions.
Galatasaray meanwhile will move into first-place with a victory over their rivals.
Basaksehir will face Ankaragucu next weekend at the Fatih Terim Stadium.
Sivasspor 0 – 0 Medipol Başakşehir
Stadium: Yeni 4 Eylül
Referee: Halil Umut Meler, Mustafa Emre Eyisoy, Cevdet Kömürcüoğlu
Sivasspor: Tolgahan Acar, Papp, Bjarsmyr, Braz, Uğur Çiftçi, Ndinga, Douglas, Rybalka (min. 90+2 Fatih Aksoy), Özer Hurmacı (min. 82 Muhammet Demir), Emre Kılınç (min. 88 Ziya Erdal), Diabate
Basaksehir: Mert Günok, Caiçara, Serdar Taşçı, Mahmut Tekdemir, Clichy, İrfan Can Kahveci (min. 78 Mossoro), Emre Belözoğlu, Visca, Soner Aydoğdu, Elia (min. 60 Bajic), Robinho (Dk. 61 Napoleoni)