United and Arsenal have both seen offers for the 24-year-old rejected, with Ajax holding out for a €50m (£42.4m) fee.
The Gunners are believed to have made three offers for Martinez, with their latest bid reportedly being £35m plus a further £4.3m in add-ons.
United have already accepted that offer and although it has also been rejected by Ajax, they are determined to reach an agreement with Erik ten Hag, who is dying to see his former Manchester defender again.
While Arsenal have yet to officially end their interest in Martinez’s signing, Goal report that United are now the side actively trying to agree a deal with Ajax after trailing their Premier League rivals in the race for his signature left himself.
Martinez is open to a move to United and has twice urged his club to negotiate in good faith with the Manchester club.
Recent reports have claimed Ajax have increased their price and are now asking £52m for the player.
However, the Dutch champions are said to be ready to reach an agreement in the coming days.
United have signed Tyrell Malacia so far this summer, signing the 22-year-old from Feyenoord.
As the club make strides in their bid to sign Martinez, ten Hag has highlighted midfield and attack as areas he is keen to strengthen this summer.
“We want to have the right players,” said ten Hag this week ahead of his side’s 4-0 friendly win over Liverpool in Bangkok.
“We’ve got a really good squad, we’re working to develop our style of play and if the opportunity arises, we’ll take it [to sign new players].
“I’ve said before that we’re definitely looking for players in midfield and I think we have a need up front. We still work for players.’
United are still in talks with Barcelona over Frenkie de Jong’s move, while Christian Eriksen has verbally agreed to a move to Old Trafford.
There is also interest in signing another Ajax star in Antony, although a whopping £71m valuation could complicate the move.
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MORE : Three things we learned from Erik ten Hag’s first game in charge as Manchester United beat Liverpool
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https://metro.co.uk/2022/07/12/man-utd-lead-race-for-lisandro-martinez-as-arsenal-cool-interest-16988926/ Man Utd lead race for Lisandro Martinez as Arsenal have cool interest | Soccer