Yanal, who led Fenerbahce to the Turkish league title in 2013-14, signed a 1-1/2 year contract with the Istanbul club, it said on its website.
Cocu, a former PSV Eindhoven manager, took over in June. Fenerbahce, one of the big three Istanbul clubs which dominate Turkish football, slumped towards the bottom end of the league during his time in charge.
The club is currently in the relegation zone, in 17th place with 14 points from 15 games.
(Writing by Ezgi Erkoyun; Editing by Daren Butler)
