The winger yesterday signed a two-year deal – and immediately linked up with his new Blues team-mates for the start of pre-season training.
Lalkovic had rejected a contract with League One Walsall in favour of dropping into the bottom division of the Football League.
He had been part of a Saddlers side which last term reached the play-offs, registering eight goals in the process.
Yet the prospect of success under Paul Cook at Fratton Park was persuasive enough to ditch League One football.
He said: ‘Pompey have ambition and the potential to go places.
‘I am not saying it is guaranteed to happen, but we have potential and the players to get success – now we have to do it on the pitch.
‘For me it is about taking one step back to take a huge one forward.
‘I know I left League One with Walsall but it was an easy decision because the offer they made.
‘I don’t think they showed me appreciation with what they offered and I don’t feel the club has the ambition to go places again.
‘If you want to keep a team together you have to invest a little bit, even though you don’t want to.
‘I don’t want to slate them, I had a fantastic time there and will only say good things about the club because they helped me and I enjoyed it there, good luck to them.
‘But I want to achieve things, I want to play as high as I can and I think I have the ability.
‘It is up to me to show it. I have the ability to get past people and want to win games for the team – which I did at Walsall.
‘If you are winning games then you are appreciated by everyone.
‘I don’t want to put pressure on myself by setting personal goals, I just want to achieve promotion with the team.’
The 23-year-old established himself as a popular figure at the Bescot Stadium as they finished third in League One last season.
With eight goals in 51 appearances, Lalkovic was a key figure in a side which suffered elimination in the play-off semi-finals to Barnsley.
Jason Demetriou is another to have departed the Saddlers during the close season, signing for Southend, and was also a Pompey target.
And Lalkovic believes he can thrive in a familiar system in his new surroundings.
He added: ‘Portsmouth also use a 4-2-3-1, which is definitely playing to my strengths.
‘I like to play on the ball and Portsmouth like to play attacking football, starting by playing it from the back. For me it is fantastic.
‘I prefer playing on the left. During the game you can change anyway, you try to find space and rotate, looking for quick one-twos.’