Manchester United might have to rebuild their most important partnership in the transfer window

he prospect of Lisandro Martinez returning for Manchester United this weekend will be a huge relief for Erik ten Hag.

The centre-back has missed each of United's last seven matches after sustaining a knee injury against West Ham United on February 4. His knee buckled under the weight of a challenge from Hammers defender Vladimir Coufal, leaving him in distress and discomfort on the Old Trafford turf.

Fortunately, Martinez did not require surgery, meaning his rehabilitation has been a lot smoother and efficient than it could have been. He linked-up with the Argentina squad in the first week of the international break, suggesting a return is imminent.

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Though United racked up five wins from the seven matches he missed prior to the pause, his presence was still sorely missed. Arguably the best signing of the Erik ten Hag era thus far, the former Ajax ace brings far more to the table than just defensive attributes.

Drafted in during the 2022 summer transfer window, Martinez brings a left-footed presence to the heart of United's defence and a varied passing range. His ability to switch the ball and ping a pass is unrivalled within United's pool of defenders.

Furthermore, he is only too willing to step out of the back-four, push into midfield and advance the ball. It was as a result of his desire and confidence to control possession inside the West Ham half that United were able to take the lead through Rasmus Hojlund in his last appearance.

In possession of the ball in the left channel, Martinez chipped the ball towards the edge of the West Ham box, in an attempt to pick out Hojlund. Though his attempted pass was cut out, it was soon regained by Casemiro, who managed to force the ball forward into Hojlund's path and he then applied the finish, crashing home his best goal for United thus far.

That goal transpired from Martinez's appetite to advance the ball and get United up the pitch. He is a ball-playing specialist and his presence has been missed far too often throughout the campaign, highlighted by his tally of just 10 appearances in all competitions.

As big a boost as it will be to potentially see him return this weekend, he will not be able to join forces with Luke Shaw on the left side of United's rearguard. The latter is still sidelined with a muscle injury and is likely to miss the rest of the season after England manager Gareth Southgate confirmed he is in a race against time to be fit for the European Championship this summer.

This season, Martinez and Shaw have started just five matches alongside each other in all competitions. Last season, the duo developed a terrific on-field rapport, creating one of the best partnerships within the team.

Often working in tandem on the left side of United's back-four, Martinez and Shaw have been key to United's first phase build-up play, bringing the ball out from the back and helping the Reds advance up the pitch. They are both comfortable in possession and happy to drive forward.

One of United's best performances this season was in the 4-3 win at Wolves at Molineux on February 1. That marked the first Premier League game Ten Hag had been able to start Martinez and Shaw alongside each other since August and United, particularly in the first half, produced some of their slickest football all season.

Shaw was a constant threat down the left, doubling up with Marcus Rashford, with Martinez also assisting with the combination play down that side. The latter and Shaw bounce off each other, hence why their partnership is so important to Ten Hag's style of play.

But amid the fact Shaw has played just 15 times this season and his fitness is becoming more and more of a concern, United could be on the hunt for a new first-choice left-back this summer. As good and as crucial as Shaw is when he is fit, he has only been available for 70 per cent of games in a season twice since joining the club a decade ago, meaning it is a department of the team in need of addressing.

With the addition of a new first-choice left-back more than possible, United will need to ensure they source one that has similar traits and will be capable of developing a strong relationship with Martinez. He needs a solid option as much as Ten Hag does.