Manchester United have signed Matthijs de Ligt and Noussair Mazraoui from Bayern Munich, the Premier League club announced Tuesday.
Fees for the pair were not disclosed by the English giants, but British media reports estimated the duo had arrived at Old Trafford for a combined £60 million ($77 million, 70 million euros).
Netherlands defender De Ligt, 25, will now join up again with United manager Erik ten Hag, having played under him at Dutch side Ajax, after agreeing a five-year contract with the option of another year.
"As soon as I heard that Manchester United wanted me, I felt an excitement about the opportunity of a new challenge at such an historic club," said De Ligt.
"In the conversations that followed, I was impressed by the vision that the football leadership set out, and the role they saw for me in it.
"Erik ten Hag shaped the early stages of my career so he knows how to get the best out of me and I cannot wait to work with him again."
De Ligt has already won league titles in three different countries with Ajax (Netherlands), Juventus (Italy) and Bayern (Germany).
He added: "I know what it takes to succeed at the highest level, and I'm determined to continue that record at this special club."
De Ligt bolsters United's central defence following the departure of Raphael Varane, with fellow summer transfer window arrival Leny Yoro in danger of being sidelined for up to three months with a foot injury sustained against Arsenal in pre-season.
Mazraoui, 26, also played under Ten Hag at Ajax, winning three league titles with the Dutch club and another with Bayern.
The full-back has also made 28 appearances for Morocco and reached the semi-finals of the 2022 World Cup.
He has signed a four-year deal with the option of a further year and his arrival comes on the day that full-back Aaron Wan-Bissaka's departure to Premier League rivals West Ham was confirmed.
"It's an incredible feeling to be a Manchester United player, and I cannot wait to walk out at Old Trafford wearing the red shirt," said Mazraoui.
"I know that I'm joining the club at an exciting time; everyone I've spoken to has the same ambition for us to win trophies together and I can feel the determination to achieve that."
The new arrivals are set to be available for United's season opener against Fulham at Old Trafford on Friday, with the Red Devils desperate to improve on last season's eighth-place finish.
That left United a huge 31 points adrift of champions Manchester City.
They did beat their local rivals in the FA Cup final before returning to Wembley last weekend to lose to Pep Guardiola's side on penalties in the Community Shield.
