Rob Dawson Correspondent 3 Minute Read

MANCHESTER, England -- Manchester United's hopes of signing a centre-back before the transfer deadline rest on clubs and agents lowering their demands, sources have told ESPN FC.

Jose Mourinho has made no secret of his desire to add a central defender to his squad, but sources insist United are adamant they will not be held to ransom in the final hours of the window and are prepared to start the season with the squad they have.

Here's where United stand on their various defensive candidates with less than 24 hours to the deadline.

Jerome Boateng

Sources said Mourinho is still keen to sign Jerome Boateng from Bayern Munich, despite reports in Germany that the 29-year-old does not want to move to Old Trafford and would prefer to go to Paris Saint-Germain.

Boateng has a chequered injury record -- he missed 181 days last season alone mainly because of hamstring problems -- and United are keen on a loan deal with an option to buy rather then meeting Bayern's demand to pay €50 million in a series of instalments.

Yerry Mina

Yerry Mina is considered a fall-back option, and while sources say United believe they can negotiate a fair price with Barcelona for the 23-year-old, who has played just six games for the Spanish side, they are refusing to pay what has been described as a "ridiculous" fee to the Colombian's advisers.

Everton and Lyon are also interested in Mina and United accept that if either club meet the demand they will miss out.

Toby Alderweireld

Toby Alderweireld remains another option, largely because Tottenham have made it clear they are willing to sell.

Sources close to both United and Tottenham insist no formal bid has been lodged, although Spurs are braced for a deadline-day offer -- which could include either Chris Smalling or Marcos Rojo to satisfy Mauricio Pochettino's desire to find a replacement before Alderweireld is allowed to leave.

The club are willing to listen to offers for Rojo, but the Argentinian will stay at Old Trafford if another defender does not come in.

United, according to sources, would want any deal for Alderweireld to reflect the fact he is refusing to sign a new contract and would be available for £25 million next summer.

Harry Maguire

Meanwhile, sources also said Harry Maguire is "intrigued" by United's interest but hope of agreeing a deal with Leicester is fading.

The 2015-16 Premier League champions insist they are under no pressure to sell after Riyad Mahrez joined Manchester City for £60 million and will only entertain offers well above the 25-year-old's market value, something United have so far refused to consider.

With United due to start their Premier League campaign against Leicester on Friday night, Mourinho will hold his first press conference of the season at 9.30 a.m. on deadline day.

The Portuguese coach said on Sunday his team could face a "difficult" season if there are no new arrivals before the 5 p.m. deadline on Thursday.

He has already signed three players this summer after Fred, Diogo Dalot and Lee Grant arrived for a combined £68 million.

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