The Pilgrims visit a sold-out Fratton Park seeking to take an advantage back into their home fixture on Sunday.
Adams’ side finished the League Two campaign with a thumping 5-0 triumph over Hartlepool last weekend, despite fielding a much-changed team.
Tonight also marks a return to the venue where they won 2-1 last month in their previous encounter with the Blues.
Adams has never before managed a team in a play-off environment.
And he has vowed to approach the occasion positively and on the front foot.
He said: ‘It will just be the same as a cup final.
‘I think the two legs will be played in a similar way.
‘It’s going to be a sell-out crowd for both games and the players will enjoy that.
‘We want to try to progress to the final and we want to be attack-minded. We don’t want to be defensive.
‘I think that when you get to this stage of the season it’s important you try to do as well as you can and use the players you have got in the best positions to affect the result.
‘The two games (against Pompey) this season have been very good matches. Both sides pass the ball well.
‘You have seen over the season we have been able to get to 24 wins, which in a difficult league is very good.
‘Over half the games we have won.’
While the Pilgrims won at Fratton Park in the league fixture, Paul Cook’s men tasted victory at Home Park back in August.
That scoreline also finished 2-1 as the Blues got their away campaign off to a flying start.
Penalties from Matt Tubbs and Gary Roberts put Cook’s side on the way, with Gregg Wylde grabbing an 89th-minute consolation.
Now the teams meet in the play-offs.
Although tight-lipped over his team’s injury situation, there are suggestions Adams has an almost full-strength squad to pick from.
And the calibre of attacking players he possesses means he is optimistic about Argyle’s chances.
Adams added: ‘We have got six or seven match-winners in our team. We have seen that over the season.
‘We haven’t had to rely on one person to score the goals.
‘We have got six or seven who can do something special to win a match.
‘When we went there the last time it was an excellent atmosphere and we will enjoy going there.’
The second leg will take place at Home Park on Sunday (6pm).