Atletico Madrid announced the loan signing of French striker Moussa Dembele from Lyon on Wednesday.
Dembele will join Atletico until the end of the season when the club will have the option to buy him permanently for around €35 million.
Atletico have paid an initial fee of €1.5 million after Dembele passed his medical on Wednesday morning in Madrid.
In a statement the La Liga club described him as a "powerful striker" with "a knack for goal".
The 24-year-old's arrival follows Diego Costa's contract being terminated at the end of December.
Dembele will compete with Luis Suarez, Joao Felix and Angel Correa for a place up front as he looks to boost Atletico's hopes of winning La Liga this season and earn a place in the France squad at the European Championships this summer.
Atletico sit four points clear at the top of the table with two games in hand over second-placed Real Madrid.
Dembele is expected to be available in early February after undgoing an operation on a broken arm, meaning he could feature in Atletico's first leg against Chelsea in the Champions League last 16 on 23 February.
After impressive spells at Fulham and Celtic, Dembele joined Lyon in 2018.
But despite a decent first season that saw him score 16 goals in Ligue 1, he had fallen out favour this term and managed just one goal in 12 appearances.
"With Dembele's arrival, we add a young yet experienced footballer who's strong both physically and as a finisher," Atletico said in a statement.
"His height also makes him a threat in the air and his speed allows him to run past the opposition's defenders."
Dembele has been replaced at Lyon by Algeria international Islam Slimani, who arrives on a free transfer from Premier League club Leicester City.
Slimani, 32, spent last season on loan at fellow Ligue 1 outfit Monaco, where he scored nine goals in 18 league appearances.
Lyon hold a one-point lead over reigning champions Paris Saint-Germain in the French top flight.