Michael Appleton challenged Pompey to up the ante on their Championship rivals as the campaign reaches its ‘defining period’.
And the Blues boss believes today’s clash with West Ham will tell his men much about their aspirations for the rest of the season.
Pompey go in to the meeting with the high-flying Hammers seven points from the relegation zone.
They are also eight points from the play-offs, with their fortunes on the pitch finely balanced.
Appleton feels a continuation of the club’s upwardly-mobile form in the league during a frantic next two months will begin to put pressure on their rivals.
There is also the reality a dip in fortunes will leave his men embroiled in a relegation dogfight.
The Pompey boss is calling on his men to up the heat in an effort to test their steel.
Appleton said: ‘It’s a defining period, without a shadow of a doubt, with the games in February and March.
‘We have 13 games in that period, with six next month, so it’s an important time.
‘The next three games – West Ham, Cardiff and Peterborough – are, for me, crucial games.
‘It almost gives you an indication of what the last part of the season is going to be about.
‘It’s one of them where you can push on to finish as high as you can in the table.
‘Or, let’s not make any bones about it, we are in a relegation scrap.
‘The next three games are the distance between no points and nine points. It might well be somewhere in between.
‘If it’s nine points from three games then it’s “come on, then” all of a sudden – “let’s see what the other teams have got”.
‘All of a sudden people will be thinking “they are on a bit of a surge – I don’t fancy playing them”.’
Pompey take on West Ham today, with Sam Allardyce’s side level on 47 points with Southampton at the top of the table.
Appleton reckons locking horns with them will reveal much about his own side and their hopes.
He said: ‘When we play a side like West Ham, who are up there, you get a fair indication of where we are as a team.
‘They are up there and have the players they have.
‘I can sit here and moan about having the smallest squad in the league and people will say I’m right.
‘But if we do beat West Ham, people will think the squad is alright.
‘You can’t do that. You have to keep improving all the time.
‘But how well we do against them will answer questions we’ve got about the players.
‘How likely is it we’ll be in the relegation scrap? Who knows?
‘I haven’t got a crystal ball but the players are more than aware how important the next three games are.
‘First and foremost, we have to think about West Ham.’