The Magpies have already endured a turbulent summer. Boss Eddie Howe departed the club on Thursday, with Newcastle moving swiftly to prepare Matthias Jaissle as his successor.
Club officials are confident the former Al Ahli boss has the potential to develop into one of Europe's leading coaches, but he arrives at a time of significant upheaval.
Newcastle have already seen Anthony Gordon complete a move to Barcelona, while Sandro Tonali has joined Tottenham.
Arsenal are now stepping up their efforts to sign Guimaraes, with the Brazil international keen on the switch to the Emirates. However, Newcastle's problems may not end there.
Manchester United are poised to add another layer of uncertainty to the club's summer plans by targeting Hall. We have been reporting on Flashscore that he has emerged as United's preferred option at left-back, and the Old Trafford club are soon expected to submit an approach for the £60 million-rated defender.
Newcastle have no desire to sell Hall, viewing him as a key part of their project. However, there is growing concern that the defender's head could be turned, much like Guimaraes', should Manchester United formalise their interest.
Sources indicate that Hall is interested in a move to Old Trafford if United follow through on their expected approach.
With Arsenal pushing for Guimaraes and Manchester United now preparing to test Newcastle's resolve over Hall, Jaissle's tenure is set to begin amid one of the club's most challenging periods in recent memory.
Follow all the transfer news and confirmed signings with Flashscore this summer.