The appointment of the former Manchester United and Everton player will come as something of a surprise after a year working as a pundit for the BBC.
Valencia have a vacancy in the role after Cathro left to become assistant to Steve McClaren at Newcastle and Neville appears to be the man they want.
Despite their confidence that a deal has already been agreed, suggestions from Neville’s camp are that talks are still ongoing.
Valencia owner Peter Lim is also a 50% stakeholder at Salford City with Neville and other members of the “Class of ‘92” which may explain why they have targeted the former defender-cum-midfielder.
In a message on their official website, Valencia seem to confirm the appointment, saying: “Phil Neville becomes the new assistant coach to Nuno Espirito Santo on the Valencia bench.
“The former Manchester United and Everton defender, who was also an assistant to David Moyes and Ryan Giggs at Old Trafford, joins us to bring expertise to the black and white with his vast knowledge of world football.”
Neville made over 500 league appearances for Manchester United and Everton during his playing career and gained 59 caps for England.
Meanwhile Neville’s old club, Manchester United are reportedly back in for Republic of Ireland defender Seamus Coleman from Everton.
United are yet to make a bid for the Republic of Ireland star, but Louis van Gaal is keen on signing a player who has been one of the most consistent performers in the Premier League in recent years.
Antonio Valencia spent much of last season as van Gaal’s regular right-back and right wing-back with Rafael suffering more injury problems and both Phil Jones and Chris Smalling more comfortable in central defence.
Chelsea are close to agreeing a deal for Fluminese’s teenage attacker Kenedy, according to reports.
The 19-year-old will join his Brazilian U20 team-mate Nathan at Stamford Bridge after the club completed his transfer from Atletico Paranaense last month.