The 21-year-old is the latest youngster to join Atletico who have also brought in Argentine forward Luciano Vietto from Villarreal since the end of last season.
Jordan Ayew scored for Lorient against his former side Olympique de Marseille as the Ligue 1 leaders were held to a 1-1 draw on Tuesday.
An early goal by Guingamp's Jeremy Pied was enough to hand champions Paris St Germain their first loss of the French Ligue 1 season, leaving Olympique de Marseille still on top despite their own defeat by Monaco on Sunday.
Bayern Munich are desperate to avoid losing a third consecutive Champions League semi-final to Spanish opponents when they host Atletico Madrid on Tuesday but coach Pep Guardiola has his work cut out to end his time in Germany on a high.
Atletico Madrid celebrated like they had won the trophy after reaching the Champions League quarter-finals by edging past PSV Eindhoven 8-7 on penalties on Tuesday following 210 goalless minutes in their last-16 tie.
What you must know about Anthony Martial, the world's most expensive teenage footballer.
Juventus midfielder Arturo Vidal smashed home a second-half penalty to earn a 1-0 win at home to Monaco in an absorbing Champions League quarter-final first leg on Tuesday, leaving the tie on a knife-edge.
Juventus will be hoping to make it 11 victories out of 11 against French teams in knockout ties when they face AS Monaco in the second leg of their Champions League quarter-final on Wednesday.
Photos from the UEFA Champions League last 16 first leg-matches played on Wednesday