Kenny Jackett is expecting a positive Pompey response at AFC Wimbledon.
The boss is certain his side can return to winning ways in League One at Kingsmeadow on Saturday.
The Blues travel to the Wombles on the back of their maiden league defeat of the season last weekend.
Jackett’s men surrendered their unbeaten start after suffering a 2-0 loss to Gillingham at Fratton Park.
However, Pompey are still three points clear at the top of the table.
Following a comfortable 1-0 success over Crawley in the Checkatrade Trophy on Tuesday, the Blues turn their attention to the league at Wimbledon.
And Jackett insists his troops are determined to get back on track against Neal Ardley’s men.
The manager said: ‘Saturday is a big game for us and it’ll have a derby feel about it with us taking our full allocation.
‘It’s a tight ground and there’ll be a passionate atmosphere I’m sure.
‘As ever, we will have to work very, very hard for any points we get out of Saturday.
‘I do (expect Pompey to respond positively).
‘We have good character and a good attitude in our group.
‘I don’t want that to fall away, particularly as we go into what's perceived as the winter months.
‘But I’m confident in our players. We’ll have a positive attitude and my players will be up for it.
‘After that, we’ll have to get the detail right to get the points.’