Thomas Lemar has described himself as "very happy with the decision" to join Atletico Madrid from Monaco.
Lemar rose to prominence in the 2016-17 season when Leonardo Jardim's young side won the Ligue 1 title ahead of Paris Saint-Germain and reached the Champions League semi-finals.
"I'm very happy to be here," Lemar told reporters.
"Antoine and Lucas have told me lots about the club. I'm very happy with the decision I made.
"I know this team demands hard work and I'll give it my all for the team. If I need to run more, I'll do it without a problem."
Lemar scored a total of 22 goals in 118 appearances for Monaco in all competitions.