The Spanish international striker stated that Nani is the type of footballer who could play in any league across the world.
“Nani is a player known the world over he could easily play in any league and would do a great job in Turkey,” Costa told Bugun.
Costa is currently on a short holiday in Turkey before returning to Chelsea for pre-season training.
Fenerbahçe have confirmed that Manchester United winger Nani will undergo a medical on Sunday.
The Yellow Canaries released a statement on the official club website confirming that the 28-year-old will arrive in Turkey for his medical and join shortly after.
The Portuguese international won four Premier League titles and the Champions League during his time at with the Red Devils.
Nani will become the Istanbul giants sixth transfer of the season after Simon Kjaer, Fernandao, Şener Özbayraklı, Abdoulaye Ba and Fabiano.