Marcos Painter warned Pompey they face a team on a high tomorrow.
The Blues travel to Field Mill to take on a side who are buoyant after winning the Blue Square Bet Premier last season.
The Stags also grabbed their first League Two points last weekend when Ollie Palmer got the goal to sink Wycombe.
Pompey are in upbeat mood, too, after brushing aside Morecambe last Saturday.
Painter delivered a sound debut in that 3-0 win.
Now it’s about building on that result as the Blues return to the road.
‘It was a good start for my debut last weekend,’ said Painter.
‘I think we’ve got the team to cause problems and win games in every league match we play.
‘Being realistic, that is not always going to be the case, though. You have to accept that.
‘You can’t take any team lightly in this division, that’s for sure.
‘Mansfield have been promoted for a reason and they are a good side.
‘So they will be on a high from that.
‘We have to be at our best, like we were in the first half against Morecambe.
‘If that’s the case, I’m sure we’ll be all right.’
Guy Whittingham’s side will be looking for their first success on the road tomorrow against Paul Cox’s team.
That’s after the 2-2 draw at Accrington a fortnight ago.
Pompey somehow didn’t come away with all three points that day, despite having 27 shots on goal against James Beattie’s side.
Painter believes a similar performance will see his team pick up a maximum tomorrow.
He said: ‘There are fine lines in winning and losing games, as we saw at Accrington.
‘Pompey were easily the better team but it doesn’t always go your way.
‘You have to stick to the philosophy of what the manager wants you to do – and stick to the philopsophy of the team.
‘If you keep working hard the right things will usually happen for you.’
Painter’s arrival stiffens competition for places in Guy Whittingham’s side.
He believes that can only lift standards in the team as Pompey look to build on last weekend’s first win.
Painter said: ‘We’ve got good competition here.
‘We are going to need that because this league is so demanding.
‘It does lift you when you get your first win.
‘The fans need lifting after what they have been through.
‘But we did things in the right way at both ends.
‘That’s the standard we’ve set ourselves now going to Mansfield.’