The Magpies remain hopeful of tying the 28-year-old down to a new contract, but sources indicate that talks - which began earlier this year - have recently cooled while the Brazilian focuses on regaining full fitness.
Negotiations are expected to resume at the end of the season, by which point his outlook could look very different.
Newcastle have a drive to retain him but uncertainty is being fuelled externally, as clubs who are likely to be competing at Europe’s top level next season are circling - aware that Newcastle may fall short of qualification.
Manchester City and Arsenal both have a long-standing interest, while links to Manchester United have intensified in recent weeks.
Flashscore sources insist that suggestions of advanced talks with United are wide of the mark, with no concrete negotiations ongoing at this moment.
The bigger concern for Newcastle is not one specific suitor - but the growing sense that Guimaraes is entering a career crossroads.
He remains settled on Tyneside and is understood to be happy at the club, yet there is a realisation internally that matching his ambitions may prove difficult if results do not improve.
Newcastle whave been knocked out of the Champions League, losing to Barcelona in the Last 16 stage, and are not in a good position to be competing at such a level again any time soon.
Silverware is already out of reach and European qualification is uncertain due to their league position, It means the club are battling a broader issue of how to convince their top players that the project remains on track.
That challenge extends beyond Guimaraes, as Sandro Tonali, Tino Livramento and Nick Woltemade are all viewed as vulnerable to summer interest - underlining the scale of the task facing Newcastle’s hierarchy.
In contrast, we understand that Anthony Gordon is currently regarded as untouchable.
Guimaraes still has a contract running until 2028, but the club are prepared to extend that deal and increase his wages in an effort to remove any doubt over his future.
The coming weeks are likely to prove crucial, as Newcastle do not just want Guimaraes to stay - they need him to commit as they look to avoid a moment when ambition and reality begin to drift apart.
