While Feyenoord stands out with their disciplined defense and high-tempo pressing under Van Persie, they don't have any standout players other than Santiago Gimenez and Quinten Timber, but as a team, they defend well.

Fenerbahçe isn't playing the football Mourinho wants right now.
John Duran has been transferred. The team is comprised entirely of players from last year.
Feyenoord is a system-oriented team, and both teams' league matches begin on August 9th.
This will be a clash of two equally strong teams.

With Jose's experience, I believe Fenerbahçe is the closest to qualifying.