Martinez is one of a number of Premier League stars being tracked by the Spanish giants, along with top summer target and Liverpool defender Trent Alexander-Arnold.
While Martinez is seen as a fan favourite in the eyes of many United followers and viewed as one of the few success stories from recent transfer windows, talkSPORT understands the Argentine is not considered off limits for any potential buyer.
The Red Devils are keen to keep young stars Kobbie Mainoo, Amad Diallo, and Alejandro Garnacho, but are open to offers for virtually every other player to help stay on the right side of PSR rules.
This includes England forward Marcus Rashford, who has previously been linked with PSG.
While it's unlikely a deal of that magnitude can be done in January, the Red Devils are willing to consider selling their £300,000-a-week academy poster boy after several months of poor performances and concerns over his off-field lifestyle.
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Los Blancos have also identified Martinez's Old Trafford teammate Diogo Dalot and Tottenham's Pedro Porro as a potential Trent Alexander-Arnold alternative. They also have a long-standing interest in Spurs star Cristian Romero.
We do talk about Bruno
Newcastle are braced for a January bid from Manchester City for star midfielder Bruno Guimaraes.
While City are not usually big spenders in the winter window, they are expected to back manager Pep Guardiola after he committed his future to the Etihad Stadium last month.
Replacing the injured Rodri is seen by Guardiola as key to getting the champions' stuttering season back on track and Guimaraes featured prominently on their list of summer targets.
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talkSPORT has been told Newcastle remain under pressure to sell players to avoid breaching Premier League spending rules and Guimaraes and Alexander Isak are their two most lucrative assets.
Patient Potter
Graham Potter remains on standby to make his managerial return at West Ham, with Julen Lopetegui still on thin ice even after Monday's much-needed win over Wolves.
Lopetegui would almost certainly have been fired had the Hammers failed to come out on top in a game dubbed 'El Sackico' with both Lopetegui and Wolves counterpart Gary O'Neil under immense pressure.
While the Hammers' Jarrod Bowen-inspired win should earn Lopetegui a stay of execution, several board members are unconvinced by the Spaniard, who faces a crunch run of gamesbetween now and the end of the month against Bournemouth, Brighton, Southampton and Liverpool.
talkSPORT understands a deal for Potter to replace Lopetegui initially until the end of the season will stay on the table, with the ex-Brighton boss keen to get back to work 20 months after being axed by Chelsea.
Lopetegui has had several dressing room fallouts with players since replacing David Moyes in the summer.
¡Bienvenido!
Brighton's latest South American star has jetted into the UK to complete his £14m move from David Beckham's Inter Miami.
Both clubs have confirmed a deal for midfielder Diego Gomez to swap playing alongside Lionel Messi to join the Seagulls, in a switch set up in the summer to be completed in January.
The 21-year-old is a key part of the Paraguay side that are on the cusp of qualifying for the 2026 World Cup and looks another smart piece of business by Brighton owner Tony Bloom.
Brighton already have Gomez's Paraguay teammate Julio Enciso on their books, as well as Argentine Facundo Buonanotte and Brazilians Igor and Joao Pedro and Colombian Pervis Estupinan - giving the dressing room at the Amex Stadium a distinctly Latino feel.