Roma have signed Amadou Diawara from Napoli for €21 million (£19m, $24m), who becomes Paulo Fonseca's third signing of the summer.
The midfielder, on international duty with Guinea at the Africa Cup of Nations, has signed a five-year deal.
Diawara, 21, joins Roma after the Giallorossi sold Kostas Manolas to Napoli for €36 million ($41m, £32m) on Sunday.
"We have been following Amadou for a while now," said Roma's chief executive Guido Fienga.
"He is a player whose talent has been clear to those in Italy for a number of years.