Manchester United's defensive line is under the microscope as the summer transfer window approaches. With INEOS poised for a major squad overhaul, the reliability of the club's center-backs has become a pressing concern.

While midfield reinforcements are a priority, the backline cannot be ignored. Injuries and suspensions have plagued the unit all season, casting doubt on its long-term stability.

World Cup winner Lisandro Martinez epitomizes this issue. Since his high-profile arrival from Ajax, his time at Old Trafford has been repeatedly interrupted by fitness problems. His latest setback—a red card against Leeds that will see him miss crucial matches against Chelsea, Brentford, and Liverpool—highlights a frustrating pattern of unavailability during the season's most critical moments.

This inconsistency has reportedly led United's hierarchy to have "serious concerns" about the Argentine's long-term fit, prompting the club to explore potential replacements in the market.

Everton's Jarrad Branthwaite has been a long-standing target, with United making formal enquiries in previous windows. However, the young defender's own injury history could be a significant red flag for a club seeking more durability.

Another name frequently linked is Bayern Munich's Matthijs de Ligt, a player familiar to manager Erik ten Hag from their time together at Ajax. While a talented and proven defender, his current situation adds another layer of complexity to United's defensive puzzle as they look to build a more resilient squad for the challenges ahead.