Manchester United have already failed with two bids worth £38.5m and £43m respectively for Martinez, but more talks have been expected between the two clubs today.
The Red Devils have identified the Argentinian as a top target on the recommendation of Erik ten Hag who worked with him at Ajax.
Ajax have been holding out for a fee of £50m, but a compromise is now expected to be reached between the two sides.
Manchester United are hopeful that a deal worth £46m will be agreed for Martinez to move to Old Trafford.
The two clubs are in advanced negotiations and a deal is expected to be worked out for the transfer soon.
Ajax have already been looking at players who could come in and replace Martinez in their starting eleven.
Arsenal have also been keen on the Argentinian but the defender prefers a move to Old Trafford.
The defender is keen to reunite with Ten Hag and has made it clear to Ajax that he does not want to miss out on a move to the Premier League this summer.
