The two coaches had clashed during the match, and their disagreement nearly turned physical after the final whistle. Ak was furious after Sahin complained in his direction and wanted to go for the long-time Bundesliga player. Members of both coaching staffs had to keep them apart, with Ak still livid.
Referee Alpaslan Sen subsequently showed the Gaziantep coach a red card for his behaviour. Ak now faces a substantial punishment.
Sahin declined to explain what sparked the incident or what happened. At the subsequent press conference, he said only: "What happened there happened there, and it stays there. I don't really want to go into such things any further."
He added: "For me, only the game matters. I never behave disrespectfully. Anyone who knows me knows that. I wish Antep every success. Those were three very important points for us."
Under contract until 2028, Sahin is in his first coaching job since his dismissal by Borussia Dortmund in early 2025. He took charge of the Istanbul club just over a year ago and has averaged 1.62 points across 45 matches.
After beating Gaziantep, Sahin's side, featuring former HSV striker Davie Selke, sit tenth in the Süperlig table. They are four points off a place in international competition.
Next Monday, Basaksehir face Besiktas in an Istanbul neighbourhood derby (17:00).