The Brazilian midfielder has been one of Arsenal’s leading targets as they seek to reinforce their squad following last season’s league triumph.
The 28-year-old is understood to be keen on making the move to the Emirates, adding further momentum to the negotiations.
Contact between the clubs has now progressed to formal talks after initial discussions were conducted through intermediaries.
People involved in the process believe the negotiations are edging closer to a conclusion, although the two sides have yet to reach a final agreement.
Arsenal previously tested Newcastle’s resolve with a 70-million-pound proposal submitted through intermediaries last month. A source at Newcastle confirmed the bid was rejected, although neither club has revealed the exact value of the unsuccessful offer.
The north London club are now expected to return with an improved bid, as it is believed a higher fee will be required to persuade Newcastle to part with their captain.
Despite the ongoing transfer negotiations, Guimaraes has travelled with Newcastle to their pre-season training camp in La Manga, Spain.
The Brazil international linked up with the squad after completing his post-World Cup break and remains with the team while discussions over his future continue.
