Inter Milan have completed the signing of Brazilian youngster Juan from Internacional.

They have reportedly also reached a deal for Colombia midfielder Fredy Guarin, as Serie A clubs strengthened their squads before the January transfer window closes.

A talented defender, Juan helped Brazil’s under-20 team win the South America Youth Championship last year.

Inter were considering loaning Juan to Novara until the end of the season but have now decided to keep him in Milan.

The Nerazzurri also agreed a loan deal with Porto for Guarin for about 2 million euros ($A2.49 million), according to the Gazzetta dello Sport.

Including a full transfer at the end of the season, the total deal would reportedly cost 11 million euros (about $A14 million).

Meanwhile, Roma have signed Fluminense winger Marquinho on loan and former Juventus midfielder Ruben Olivera has become Fiorentina’s fifth January signing after joining from Lecce.

Olivera, who has featured 11 times for Lecce this season, has reportedly signed a two-and-a-half year deal with the Tuscan club.

The Uruguayan was at Juventus from 2002 to 2010 but made just 39 appearances for the Serie A club and was shipped out on several loan spells.

Fiorentina have already signed Amauri, Guido Pizarro, Mounir El Hamdaoui and Kenneth Zohore this month.

The transfer window closes on Tuesday night.