Ian Hendon has been named as Waterford FC coach for their promotion/relegation play-off final against UCD on Friday.
According to a club statement, the 49-year-old will support Dave Bell, the staff and players who are "united as a collective" for the hugely important clash.
Hendon featured for the likes of Tottenham Hotspur, Sheffield Wednesday and Barnet during his playing career.
He previously worked as West Ham's development coach under Sam Allardyce.
Hendon has also worked as a coach with Leyton Orient.
Waterford must beat UCD to avoid relegation to the First Division, having featured in the Premier Division since 2017.
The club's fans were furious at the surprise move to sack Marc Bircham ahead of the play-off.
“I am extremely disappointed to have had to make this tough decision, especially given the huge match we have facing us on Friday,” club owner Richard Forrest said in a statement.
“I feel we were backed into a corner, given an ultimatum, which as an owner left me no choice but to act now in the long-term best interests of the club.
“I would have only made this decision when left with no other option and I take no personal satisfaction from it.”