Ajax have announced the signing of Lisandro Martinez from Argentine club Defensa y Justicia.
The 21-year-old central defender, who can also play at left-back, signed a four-year contract with an option to extend for a fifth season after completing a medical on Monday.
He played a key role for Defensa in 2018 as they finished second in the Primera Division, four points behind Racing, and earned his Argentina debut in March when he featured against Venezuela.
And Ajax director Marc Overmars says a lot is expected of him in Amsterdam as he teams up with compatriots Nicolas Tagliafico and Lisandro Magallan.
"Martínez is a left-footed player who can play in multiple positions at the back," he told the club's website. "He is a defender who wants to play forward. He brings along a certain mentality that we can use well here, comparable to what his fellow countryman Nico Tagliafico shows.
"And Lisandro is still young, so we expect that he will develop further into an even better player in the coming years."
Martinez made 55 appearances for Defensa after initially joining on loan from Newell's Old Boys in 2017, making the move permanent last summer and quickly developed a reputation as a fast, attack-minded player.
He is Ajax's fourth signing ahead of the new season, with the Eredivisie winners and Champions League semi-finalists having already snapped up centre-back Kik Pierie from Heerenveen, goalkeeper Kjell Scherpen from Emmen and attacking midfielder Razvan Marin from Standard Liege.
While star midfielder Frenkie de Jong has already agreed to join Barcelona this summer, 19-year-old captain Matthijs de Ligt is still being linked with the Catalan side as well as Paris Saint-Germain and Juventus and Hakim Ziyech is expected to seek a move after winning the domestic double with the Dutch giants.