Netherlands midfielder Kevin Strootman has joined Marseille from Roma in a €25m (£22.7m) deal.
The 28-year-old played 44 times last season as Roma finished third in Serie A and reached the semi-finals of the Champions League.
Marseille announced the signing with a Fortnite-style video.
"The club would like to thank Kevin for his service over the years, and wishes him all the best for the future," Roma said.
Strootman played under current Marseille coach Rudi Garcia when he joined Roma from PSV Eindhoven in 2013.
He is the third high-profile player to leave Roma this summer after Brazil goalkeeper Alisson joined Liverpool in a deal worth up to £66.8m and Belgium midfielder Radja Nainggolan joined Inter Milan for £33m.