Istanbul Başakşehir on Thursday announced the departure of manager Abdullah Avcı, who will head across town to take charge of rival Beşiktaş.
"Following discussions that we have had with Abdullah Avcı, we have come to the joint decision to part ways," Başakşehir said in a statement.
Avcı will take over at Beşiktaş from Şenol Güneş, who is leaving to become the manager of the national team. Avcı's contract is expected to be for three years.
Avcı established a star reputation at Başakşehir, a relative newcomer to Turkey's Süper Lig.
The 55-year-old coach has become one of the most respected in the country, known for a steely calm and tactical ingenuity.
The former striker trained the national team between 2011 and 2013.
But he really made his name at Başakşehir after taking over in 2014, turning the club into the "fourth giant" of Istanbul football, rivaling the historic dominance of Beşiktaş, Galatasaray and Fenerbahçe.
For all his achievements, he never managed to get his hands on the championship trophy. During Avcı's spell Başakşehir twice placed 4th, once 3rd and twice finished as the runner-up.
It looked as though that might change this season, with Başakşehir topping the table for several weeks, only to be pushed into second place at the last minute by Galatasaray.
Former international midfielder Okan Buruk is tipped to become Avcı's successor at Başakşehir.
