Pompey will not be wanting to rely on other sides dropping points to secure a League One play-off spot.
They know that victory over Accrington at Fratton Park on Sunday would guarantee an extension to the campaign.
Blackpool, Sunderland and Lincoln have already booked their place in the end-of-season lottery, with the Blues currently in front of Oxford and Charlton for the final spot.
And Marcus Harness is delighted that Pompey have such an important prize to play for on the final day.
He said: “It’s a big opportunity for us and the most important thing is that everything is in our own hands on Sunday.
“We’ve been preparing all week, so now we’re looking forward to actually playing the game and trying to get the job done.
"It’s a big opportunity for us and the most important thing is that everything is in our own hands on Sunday."
“There were some points in the past few weeks when it seemed like we might have messed up our chances.
“But we managed to get back on track and know that as long as we win this weekend, there’s no way of us being caught.
“We're aware of just what we have to do and all the players will be giving absolutely everything to achieve that.”
The fixture comes just 12 days after Pompey and Accrington took part in a six-goal thriller in the north-west.
Harness said: “I think it helps us massively to be at our own ground and it should be a very different game to what we saw up there.
“There’s a positive mood around the place and I think we owe Accrington one after what happened the other night!
“The only disappointing thing is that there are no fans on Sunday because that would stack the odds massively in our favour.”