Martinez joined United in a £56.7 million deal from Ajax last summer but questions were immediately raised over the 5ft 9in Argentine’s lack of height in comparison with other Premier League centre-backs.

However, Martinez has been one of United’s standout performers this season and Soeness believes Erik ten Hag’s side have been worse off since the 25-year-old was sidelined last month due to a broken metatarsal.

‘United are the ones who have to keep their nerve in these all-important two weeks,’ Souness wrote in his column for MailOnline.

‘I ascribe some of their fall-off in form to the absence of Lisandro Martinez. They’ve have won only three of their six league matches since he was injured at Sevilla.

Lisandro Martinez quickly established himself as a key part of Manchester United’s defence this season

‘I thought Martinez would get found out in the Premier League because of his physique.

‘I still believe that will be an issue for him going forward – but he is one who leads from the front for United and has a big influence on those around him.’

Souness also dismissed suggestions that potential transfer targets would reject a move to United or Liverpool if they missed out on a place in next season’s Champions League.

‘If United end up winning the FA Cup, on top of the League Cup, that would have been a great season for them,’ Souness wrote.

‘But they’re still way short of challenging for the title and Champions League. A club of their status needs to be challenging for those.

‘Claiming a top-four spot can also help teams secure your transfer targets, though the majority of players who get a chance to sign for either Liverpool or United are going to take it. These are not just major football clubs. They’re institutions. Anyone who has a chance to play for either of them would jump at it, Champions League or not.’