Ian Saunders has been drafted in to manage the Royals in the absence of Graham Rix.
Former Pompey manager Rix misses the game for personal reasons.
Saunders was sacked as boss by Winchester City earlier in the week.
But Portchester chairman Paul Kelly wasted little time in getting Saunders on board.
He led Petersfield to the Wessex premier title in 2015.
Kelly admitted he was forced to take charge of the Royals’ 2-0 defeat at Brockenhurst on Tuesday night.
And he revealed that Saunders will carry on a role with Portchester when Rix makes his return.
‘When I heard of the events at Winchester I gave Ian a cheeky phone call to sound him out,’ said Kelly.
‘Within 15 minutes of meeting him he indicated he was up for the challenge.
‘We shook hands on a deal.
‘He has an excellent track record at our level, having taken Petersfield to the title and promotion.
‘That season I think his team only lost two league games.
‘In Graham’s absence we needed to get someone in because I have had to hold the fort.
‘At Brockenhurst in midweek I was mini-bus driver and managed the team from the dugout.
‘It has been agreed that when Graham comes back the two will work together for next season.’
The Royals have endured a miserable time of late having won just one of their past eight league games.
Portchester have slipped to eighth in the table and are no longer in contention for promotion.
Kelly had ambitions of stepping up to the Southern League at the start of the season.
But a combination of injuries, suspensions and the departure of some key figures have gone against them.
At the start of the season coach Michael Birmingham departed for Horndean.
Fellow coaches Steve Johnson and Pete Stiles have subsequently left.
Now with Saunders on board Kelly believes the club can start to build, ready for next season.
‘We are already looking towards the future,’ Kelly added.
‘Off the field the club is ready to move up to the next level.
‘On paper I still believe we have the best team in our league when everybody is fit and available.
‘Maybe what we have lacked is enough depth in our squad.
‘At times we have had to rely on too many youngsters.
‘Our aim is to save a bit of face by winning as many games between now and the end of the season.
‘We still want to finish as high as we can.
‘We’ve told the players to enjoy their football.’
The Royals hope to have strikers Lee Peacock and Andy Todd available for selection against Andover.