According to 'Sky Sports', Newcastle have moved for the Argentine after their attempt to sign Barcelona's Marlon Santos fell flat.
No fee has yet to be agreed between the sides, but it is understood that the two clubs are in the same ball park, hence why Swansea have allowed Fernandez to travel for a medical.
The 29-year-old is expected to cost the 'Magpies' around £6m as they look for cover for Florian Lejeune after he was ruled out long term with a serious knee injury.
Fernandez joined Swansea from Napoli back in 2014 and has been a regular starter for the Welsh side ever since.