The Red Devils are eyeing a move for the 24-year-old Argentine international as new manager Erik ten Hag looks to bolster his defensive ranks.
Martinez has also emerged as a priority target for Arsenal. The Sun claims that the Gunners have already seen a a £25 million bid for the Argentine defender rejected by Ajax.
The aforementioned report also states that Ten Hag is in regular touch with his former team regarding Martinez's situation.
During his time at Ajax, the Dutch manager signed the 24-year-old from Argentine side Defensa y Justicia in the summer of 2019.
Over the last three years, Martinez has established himself as one of the key players for the Eredivisie giants.
Martinez, a left-footed central defender, boasts solid ability on the ball and his passing out of the back is also impressive.
The former Newell's Old Boys defender is also versatile, capable of playing at left-back and as a defensive midfielder as well.
Manchester United struggled defensively last season, and Ten Hag is keen to strengthen his backline.
While United skipper Harry Maguire regularly made headlines for all the wrong reasons, Raphael Varane also failed to impress in his debut campaign at Old Trafford.
Eric Bailly, Victor Lindelof and Phil Jones are among the other centre-back options available to Ten Hag.
The new Manchester United manager wanted another Ajax defender, Jurrien Timber, to follow him to England, but the Dutchman rejected a move, as per The Daily Metro.
Arsenal target Lisandro Martinez will be an excellent signing by Manchester United
Manchester United are in dire need of bolstering the heart of their defense, and a move for a left-footed centre-back makes a lot of sense.
Martinez is a calm and composed ball-playing defender who could make the left centre-back position his own.
Also capable of playing as a left-back, the Argentine international would also offer some much-needed depth in that position. He made 24 appearances in the Eredivisie last season, recording one goals and three assists.
Ten Hag already knows the defender well, which could help United pip Arsenal in the race for Martinez.