Ruben Amorim could soon unleash a new long-term Manchester United partnership

Planning to sign two centre-backs in the summer transfer window, it was quickly debated who would make up Manchester United's first-choice paring in the heart of the defence.

Lisandro Martinez, despite his injury struggles last season, has been an indispensable figure since joining the club from Ajax in July 2022, establishing himself as arguably the club's best signing of the Erik ten Hag era. His ball-playing credentials and the fact he is left-footed have seen him make the left-sided centre-back berth his own over the last couple of years, meaning there was next to no chance to him being dislodged from United's strongest starting line-up.

But having said farewell to Raphael Varane at the end of last season, United had no choice but to strengthen at centre-back, despite already having Harry Maguire, Victor Lindelof and Jonny Evans, who signed a new contract, on their books.

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United, adopting a new transfer policy, won the race for Leny Yoro in July, signing him from French club Lille in a deal worth €70million. The defender, who turned 19 last week, had established himself as one of Europe's most promising centre-backs and was also being admired by Real Madrid.

Just under four weeks after swooping for Yoro, United signed Matthijs de Ligt from Bayern Munich, reuniting him with Ten Hag. The duo had previously worked together at Ajax prior to De Ligt moving to Juventus in 2019.

By the time De Ligt had put pen to paper on a five-year deal at Old Trafford, United were already without Yoro. The Frenchman fractured his metatarsal in the first game of United's pre-season tour of the United States in July and was ruled out for several months.

It meant De Ligt was immediately in pole position to start alongside Martinez at centre-back. After watching Maguire start United's opening two Premier League games of the campaign, the Netherlands international has since started eight of the last nine league games, establishing himself as United's first-choice right-sided centre-back under both Ten Hag and more recently Ruud van Nistelrooy.

However, following the appointment of new head coach Ruben Amorim, the landscape of United's backline is likely to change. The former Sporting Lisbon boss is expected to install a 3-4-3 formation in his quest to transform United's style of play.

The 3-4-3 formation was the bedrock of Amorim's success at Sporting and he must stick to his principles if he is to be a success at Old Trafford. Switching to a 3-4-3 means a shift to a three-man defensive line, featuring three centre-backs, supported by wing-backs either side.

Amorim took charge of training for the first time on Monday and video footage that was captured appeared to show him working on a three-at-the-back system. Yoro was among those who featured in the session.

The youngster has been back out on the grass at Carrington for a few weeks and it is hoped that he will be in contention to make his competitive debut for United sooner rather than later. Amorim could be asked to an issue an update on the defender's progress when he meets the media for the first time later this week.

The prospect of Yoro soon being back available could be significant to Amorim's thinking. Signed for a massive fee, he was not brought to Old Trafford to sit on the bench, meaning he will, once back up to speed, expect to start week-in, week-out.

United's decision to appoint Amorim when they did could not have been better timed for the Frenchman. The expectation of a 3-4-3 system being introduced means an extra centre-back slot in the starting XI.

Having spent so much money on Yoro and De Ligt, United chiefs will expect both of them to become staples in Amorim's first-choice backline, operating alongside Martinez.

Aged 19, 25 and 26 respectively, Yoro, De Ligt and Martinez have the capacity, should they hit it off as a trio, to form a long-term partnership and create a new-look United spine for years to come.

Yoro is considered as one of the most promising centre-backs in football, De Ligt is not without his qualities, despite an indifferent start to life in England, and Martinez is one of the best in the business when it comes to playing the ball out from deep areas.

On paper, it is a back-three with the potential to thrive under Amorim's coaching, offering United the opportunity to start afresh at the back.