LISBON: He will become the most expensive player ever in Portuguese football when he completes a 50 million-euro ($56.5 million) move to Real Madrid this July, but before that Eder Militao will attempt to help Porto overcome Liverpool in the quarter-finals of the Champions League.

The 21-year-old Brazil international last month became Madrid's first signing since Zinedine Zidane returned to the club as coach for a second spell.

A central defender who can also operate at right-back, Militao will join the Spanish giants on a six-year deal until 2025 and reinforce a Real backline that has often been diminished by injuries this season.

His transfer will eclipse the previous Portuguese record set by Colombia playmaker James Rodriguez, who left Porto for Monaco in 2013 in a move worth 45 million euros.

"Real have made a good signing," said Porto goalkeeper Iker Casillas, who starred with both Real and Spain for over a decade.

"He's a boy who was talked about a lot in Brazil and who Porto gambled on because he was very young. He's shown real character and great desire to prove his worth," Casillas told Spanish sports daily As.

A native of Sertaozinho, in southern Brazil, Militao made his international debut for the five-time World Cup winners in September.

He earned his second cap in a 1-1 draw with Panama last month and will hope to be part of Tite's Copa America squad for this summer's tournament in Brazil.

"We started to track Militao while he was at Sao Paulo," Brazil national team coordinator Edu told Marca.

"He had this special strength, something very different. Real paid what they paid because they came to the same conclusion as us: he's a player who has a very promising future."

Militao broke into the Sao Paulo first team in January 2017 after rising through the club's youth ranks, and 18 months later he was snapped up by Porto for seven million euros.

His adaptation to European football was swift and he quickly earned a starting place in Sergio Conceicao's side.

While the January arrival of Portugal veteran Pepe, a three-time Champions League winner with Madrid, forced Militao over to right-back, he will resume his partnership with Felipe for Tuesday's first leg at Anfield with Pepe suspended.

The pair will face a tall order against Liverpool's front three of Mohamed Salah, Sadio Mane and Roberto Firmino -- who combined to put five goals past Porto on the way to a 5-0 aggregate victory in last season's last 16.

But it should be a welcome challenge for Militao ahead of his move to the record 13-time European champions.