Mario Pasalic has joined Atalanta on a permanent deal after six years at Chelsea without making an appearance.
The 25-year-old moved to Stamford Bridge in 2014 but spent his time at Chelsea on loan at five different clubs.
Pasalic was loaned to Elche, Monaco, AC Milan and Spartak Moscow before spending two seasons with Atalanta.
Last season, Pasalic helped the Serie A club to third place, their highest ever finish, and played a role in their run to this year's Champions League quarter-finals.
His 15 goals in 75 games for Atalanta has encouraged them to exercise the option to sign the Croatian international permanently for a reported fee of £13.5m.
Atalanta tweeted: "Mario Pasalic stays with us! Our #88 is an Atalanta player on a permanent basis!"
Chelsea said: "Atalanta have today exercised their option to sign Mario Pasalic on a permanent deal. The midfielder is currently spending his second year on loan at the Italian side and will now join them permanently ahead of next season.
"We thank Mario for his service to the club and wish him the best of luck for the next chapter of his career."
The sale helps Chelsea recoup some of the fee they paid for German forward Timo Werner last week.