USP host Rovers in the first ever Wessex Premier derby between the two clubs at the Victory Stadium (7.45pm).
It is only the third time the pair have met in a league game, after facing each other in Baffins’ maiden Wessex campaign in 2016/17.
Back then, current USP boss Tom Grice was in his club’s starting XI for a 4-1 early-season loss in August 2016.
Goals from Callum Dart (2), Ryan Pennery and Jamie White gave Rovers a 4-2 Division 1 win at the Victory Stadium. Mig Dark, now at Moneyfields, grabbed both USP consolations.
Baffins were handed a shock in the return fixture, though. Two days after Christmas, US triumphed 3-1 away against a Rovers side that ended up winning promotion in their first season at Wessex level.
Harry Jackson, now at Horndean, was among the scorers alongside Perry Easton and Dark.
Current Portchester defender Zak Sharp was also in the winning USP side that day while Frankie Paige - who remains at the club - came on as a sub.
USP are aiming to end one of only two unbeaten Wessex Premier records in 2021/22. Baffins have won four and drawn two of their six games so far. After twice coming from behind to draw their opener 2-2 at Fareham Town, Rovers have only conceded one goal in five matches – in a 1-1 draw at Alresford last weekend.
Grice would no doubt like a similar defensive record – USP have shipped 18 goals in their last five league and cup outings, including 5-0 thumpings by Bashley and Hamworthy (the Hammers possess the only other unbeaten Wessex Premier record).
Tonight’s game is USP’s first mainland PO postcode league derby since those two meetings with Baffins five years ago.
But they then face two more in the space of four days - travelling to Fareham Town next Saturday before an intriguing city derby at Moneyfields next Tuesday.
As has been well documented, a large chunk of last season’s US Portsmouth squad followed former boss Glenn Turnbull to Dover Road in the summer.
That will add a huge dollop of extra spice to a meeting between two clubs who were two divisions apart last season and who have never met in a Wessex League game.