The left-back believes he can thrive on regular first-team football at Fratton Park.
The 20-year-old has agreed a move from Wolves on loan until the end of the season.
And he's out to show the Blues they were right to give him an opportunity to play.
Deslandes said: 'It's a great move for me and I'm delighted to be here. It's a chance to play regularly and that's what I need.
'For a young player it's a good chance to play because it's not good enough to just train. At some point you need to start playing games and that's what I need.
'I'm thankful for that chance and will give everything for Portsmouth.'