The 37-year-old played more than 500 games in 19 seasons with Italian giants Juventus before joining Sydney in the off-season on a contract reportedly worth A$2 million (£1.26m) a year.
A-League and Sydney FC officials touted the contract as the biggest in Australian professional sport and predicted his arrival to have an impact similar to that of former England captain David Beckham's move to the LA Galaxy in the United States.
However, Del Piero made a quiet start for Sydney and was overshadowed by Wellington's Belgian striker Stein Huysegms and teenager Louis Fenton, who scored either side of half-time for the home side in front of more than 12,000 fans.
"I'm not satisifed, because we lost," said Del Piero, whose supply of ball was choked off by the Phoenix midfield. "But it was the first match and we need to improve.
"We need to play a few more times together ... (but) Wellington played a very good match. They were strong. They held the ball. They had ideas. Congratulations to the Phoenix."
Del Piero said it was too early for him to judge the standard of play in the A-League, having only arrived in Australia three weeks ago and having limited pre-season time with his new team.
"We don't need to make judgement now," he said. "After 10 matches we can talk in general, but not now."
Much like his performance on the pitch, Del Piero's arrival in New Zealand's capital on Friday was low-key, greeted by only a small group of fans at the airport while other passengers appeared bemused as to who was attracting so much attention.
Administrators have positioned Del Piero as a talisman for A-League, which began its eighth season on Friday, in the hope he will raise the profile of the sport amongst fans, the media and businesses in a crowded sporting marketplace.
Despite booming youth participation rates, professional soccer has struggled to make inroads in Australia against the entrenched rival codes of Australian Rules and rugby league and union.
It also has fitful support in rugby-mad New Zealand, with the Phoenix's average attendances falling from their first season of more than 11,000 per game to just over 8,200 for the last four.
The national team have also drifted out of New Zealanders' minds since reaching the 2010 World Cup finals, with the All Blacks again taking centre stage by winning last year's rugby World Cup.
The A-League has also been hampered by the financial collapse of the North Queensland club, bailouts from Football Federation Australia to keep other franchises afloat, and two bitter, and very public, disputes earlier this year with individual club owners.
Wellington accountant Antony D'Esposito, who bought an Italian flag to Wellington Regional Stadium and was wearing a Juventus shirt, was optimistic about the impact Del Piero could have.
His Juventus-supporting grandfather had emigrated to New Zealand and instilled the same passion for the Turin club in his grandson, and he had come to the match because of Del Piero.
"I was super-excited. I followed the transfer on the websites and the first thing I did when it was complete was see when they (Sydney) were playing Wellington and I couldn't believe my luck," the 22-year-old said. "I bought the tickets straight away."
D'Esposito felt Del Piero's presence in the league would create more interest. He said he himself would attend matches more regularly after only coming for play-off games or "on sunny days" in the past.
He said the influx of top talent into the A-League sparked more interest in the sport and rekindled memories of the national team's final qualifying match for the 2010 World Cup finals against Bahrain.
"When people like this come to the league, it has got me as excited as when New Zealand played Bahrain.
"At the end of the day I have come here to watch Del Piero, but him being here will put soccer and the A-League on the map a bit more."
Despite his optimism, D'Esposito sounded a note of caution about the 2006 World Cup winner's influence.
"He has got a massive expectation (on him) and if he doesn't play beyond everyone else in the league then getting these type of players to play in the league is going to be a big (problem) in the future.
"It could be a bit of a letdown if he doesn't (meet expectations) but I'm very optimistic he will.
"I think it is a huge thing for the league ... hopefully this is the start of something special."