Perth did their best during the final few moments, including five minutes of time added on, but couldn't find their way back in to the contest.
Paul Ifill, who during the week signed a new contract with the Wellington club, looked at home out on the wing as he and Bertos switched sides throughout the game.
Ifill had his moments in the match, but would maybe have liked to have the ball at his feet a bit more, although Perth's defence did well to keep a lid on the Barbados international.
The Phoenix ended the game with 10 men though, after substitute Mirjan Pavlovic was shown a straight red card.
It was a disappointing moment for Pavlovic who had impressed during his past few cameos off the bench after he recovered from a badly broken arm.
Sigmund and Phoenix skipper Andrew Durante ran a tight ship in the heart of defence and despite one hairy moment from Tony Warner the big keeper kept a valuable clean sheet.
Shane Smeltz, a former Phoenix favourite who won the golden boot crown during his time with the club, had a quiet game in the white and purple of the Perth strip.
An uneventful first half saw Tim Brown and Ifill collect yellow cards, while both goalkeepers each had one save to make.
Phoenix players appeared unimpressed with the officials as both sides trudged off at the break, which was perhaps in regards to a late penalty shout from the home side.
Perth also thought they had claims to be awarded a spot kick for an early hand ball from the Phoenix, but referee Ryan Shepheard waved play on.
Danny Vukovic, who became the first goalkeeper to score in the A-League when he banged home a penalty for the Phoenix last season, returned to his former team for the first time.
He received the customary boos when his named was announced before the game, but looked assured between the sticks throughout the match and made a sharp stop during the first spell.
It appeared during the second half that he would be subbed, but after a long injury break he recovered and played out the match although there was little he could do about Sigmund's late effort.
