It follows on from reports in San Sebastian’s Cadena Ser station on Wednesday evening that a deal to take the Brazilian striker to Molineux was in place.
The 29-year-old was included from the start in his side’s 2-0 Copa del Rey victory at Cordoba on Wednesday in which he netted twice.
Nuno told reporters, in quotes carried by Marca: “The negotiations are ongoing, but nothing has been signed yet, so I prefer not to talk too much about the situation at the moment.
“When Willian Jose is a Wolves player I will speak more in depth about it, but there is still nothing signed.”
The Brazilian striker first moved to Spanish football in 2013 when he joined Real Madrid – but he made just one first-team appearance for the club and mainly played for the club’s Castilla team.
He then scored 10 goals in separate seasons at Real Zaragoza and Las Palmas but it is at La Real where he has made his name with 60 goals across four and a half campaigns.