Steve Cotterill issued a rallying cry to Pompey supporters and told them: We need you with us.
The Blues boss knows there are plenty of the Fratton faithful facing a tricky decision this weekend, with the final Saturday before Christmas notorious for shopping misery.
But Cotterill has urged Pompey fans to forget high street hell and come out in force for the club's first home game since mid-November as Scunthorpe visit the south coast.
It is set to be a key match for the Blues, who are eager to build on their recent promising form against their struggling opponents.
Cotterill is not taking Scunthorpe lightly, though, and wants Blues supporters to pack into Fratton Park tomorrow to cheer on his men.
He said: 'We need as many fans as we can get there as possible.
'I know it's the last shopping weekend before Christmas and I would tell them to go sick on Monday or Tuesday because it won't be so busy at the shops!
'It will be heaving around the shops on Saturday. The guys who are going to get dragged around the shops on Saturday – forget that!
'We need a big crowd but we don't want them coming along just expecting everything to happen.
'Scunthorpe will be given full respect but it's really a weekend where we need the crowd right behind us and to make it a really intimidating place.
'We need those three points this weekend.'
After excellent back-to-back wins on the road at Swansea and Norwich in the previous two fixtures, Cotterill is eager for his side to boost momentum with a first home win since the 2-1 success over Nottingham Forest in October.
Cotterill said: 'It's important for us to make the most of this home game.
'We've had two really good results away from home and we need to build on that.
'We do like playing at home and we play well there – not that we haven't played well away from home lately.
'I think the opposition know that it's a very, very difficult place to come to get a result and that's down to our fans.
'We're looking forward to being back there.'
With Pompey set to embark on a difficult run of games over the Christmas period, Cotterill is looking for the perfect boost to what is always a pivotal period of the season.
He said: 'This game doesn't bring us into the Christmas period – it's the Millwall home game that will bring us into that really tough run of games over a very short period of time.
'That one will be taxing – not that this one won't be.
'We are very much on our mettle this weekend.
'I probably will set a points target for Christmas but I need to get this week out of the way first.
'This is the important one – it's a very, very important game in the grand scheme of things.'