Paul Cook has insisted Pompey are aiming to catch the teams above them in the table.
The Blues boss said he was firmly focused on making up ground on leaders Doncaster Rovers and second-placed Plymouth rather than worrying about Luton, who sit directly below them in the standings.
Tuesday’s 2-0 win over Crawley moved Pompey into League Two’s top three – six points behind the Pilgrims and 10 adrift of Donny.
Luton, who are fourth, can overtake the Blues if they win their game in hand.
But Cook admitted those teams above his side are his priority.
‘If I was sitting two points behind Luton I’d be saying the same things I’m saying now.’ said Cook.
‘Whenever you get into a league position the most important thing is looking up, not behind you. If we win Saturday we know we’ll be in a healthy position.
‘For us, Luton will go and do what they do, and we wish them well, as we do for all the teams around us, but we’re now concentrating on trying to catch the teams above us.
‘That’s how this game has to be.’
Pompey’s form this season has been hampered by inconsistency at key times, with a 3-0 win away at Carlisle duly followed by just one point from two winnable home games.
But Cook has praised his players’ response to that disappointment,
‘What we’ve learnt all along is that it is a roller-coaster for us all.
‘If we get put down, these lads continually get up, but the challenge for us all now is can stop getting put down.
‘If we win football games we’ll get exactly where we want to be.’