Manchester United are chasing another centre-back this summer.

With Phil Jones and Chris Smalling failing to convince, Victor Lindelof enduring a torrid debut season and Eric Bailly falling out of favour late in the campaign, it's becoming increasingly clear that Jose Mourinho wants another man in the centre of his defence.

The most recurring link this summer has - of course - been to Tottenham's Toby Alderweireld.

With the Belgian's contract expiring in 2019, time is running out for Spurs to collect a reasonable fee for their player and even an extension clause does little to improve their chances.

If Tottenham extended his deal by another year, a £25 million release clause would come into play.

United's interest in Alderweireld

As a result, the north London club want a fee similar to that paid by Liverpool for Virgil van Dijk and it's believed that United would prefer a move this summer.

Alderweireld is now three seasons deep into his spell with Tottenham and has thoroughly impressed in the Premier League, despite recent injury problems.

Few days have gone by without an update on United's chase for the 29-year-old.

Mourinho's eight-man shortlist 

However, high-level sources at United have told the Manchester Evening News that the club's scouts are actually unconvinced by the Belgian and are advising that they look elsewhere.

Alderweireld is confirmed to be on the Red Devils' shortlist but isn't the preferred name.

Scouts have raised concerns about the player's 'profile' and he is not a '100% target' this summer.

So, who else are United considering? Well, the M.E.N. leaked the eight-man shortlist within their report, naming a wide range of centre-backs that the club is 'interested' in.

The list reads: Raphael Varane, Jerome Boateng, Kalidou Koulibaly, Milan Skriniar, Alessio Romagnoli, Jose Gimenez and Caglar Soyuncu.

Boateng, Varane and Koulibaly are the eye-catching names on the list and would undoubtedly come at quite the cost were Mourinho to focus his search on one of them.

Meanwhile, Inter Milan's Skriniar, AC Milan's Romagnoli, Atletico Madrid's Gimenez and Freiburg's Soyuncu prove more left-field but still very intriguing targets.

Of course, the club won't actively pursue all eight defenders yet it's interesting to have an insight into Mourinho and Ed Woodward's thinking for their new centre-back.

You would think that United fans would take Alderweireld over the majority of the names listed, barring the likes of Boateng and Varane.

Nevertheless, the concerns raised by scouts are making a deal with Tottenham look increasingly unlikely and no more so when you consider the asking price.

The summer is still young and Mourinho has plenty of time to explore his options going.

It will be intriguing to see how that list of eight narrows down in coming weeks and just who that 'preferred name' amongst the bunch, really is.

Who do you think Man Utd should buy at centre-back this summer? Have your say in the comments section below.