Manchester United announced Wednesday they had completed the signing of Argentina defender Lisandro Martinez from Ajax for a reported fee of £56.7 million ($68 million).
Martinez, who has signed a contract until 2027 with the option to extend for a further year, said it was an "honour" to join the Premier League giants.
Martinez, 24, won two Eredivisie titles working under Old Trafford chief Erik ten Hag at the Dutch giants, having moved to Amsterdam in 2019.
A centre-back who can also fill in at left-back or as a defensive midfielder, the Argentine is aiming to win trophies at United after signing a five-year deal.
Martinez said: "It’s an honour to join this great football club. I’ve worked so hard to get to this moment and, now that I’m here, I’m going to push myself even further.
"I’ve been lucky enough to be part of successful teams in my career and that’s what I want to continue at Manchester United.
"There will be a lot of work to get to that moment, but I firmly believe that, under this manager and coaches, and together with my new team-mates, we can do it.
"I want to thank Ajax and their fans for all the support they gave me. I had an unbelievable time there but feel the moment is right to test myself in another environment.
"Now I am at the perfect club to do this."
Martinez is the third signing of the summer at Old Trafford following the arrival of left-back Tyrell Malacia from Feyenoord and signing of free agent Christian Eriksen.