Though short of recent match play, the 37-year-old Del Piero played a full 90 minutes for his new club in its match against the Wellington Phoenix in New Zealand but couldn't prevent defeat.
Former England striker Emile Heskey played 70 minutes in his debut for the Newcastle Jets, who were beaten 2-0 by Adelaide United, while Japan star Shinji Ono took the field in the 59th minute of the Western Sydney Wanderers' first-ever A-League match that ended in a 0-0 draw with Central Coast.
While none of the league's glamor signings finished on the winning side, all showed enough to suggest they might bring the gravitas to the league that their teams and football officials are hoping for.
The spotlight in the opening round fell most brightly on Del Piero, the costliest and most high-profile signing in the league's eight year history and a global star after his record 513 matches for Juventus and 92 appearances for Italy.
He managed only 70 minutes of match play in a low-key internal club match in his leadup to his A-League debut but showed no lack of fitness in a relatively fast-paced match.
Del Piero was partly outshone on a damp night and in a match played in front of 12,057 fans by former Belgium striker Stein Huysegems, who failed to score in his 15 internationals, but provided Wellington's opening goal.
The second goal fell to Del Piero's marker, 19-year-old Kiwi Louis Fenton, who was also making his A-League debut and provided the match's signal moment of skill to score from a diving header.
Del Piero showed some fine touches, nutmegging opponents, turning and placing deft passes at the feet of his teammates. He had shots on goal in the 13th and 74th minutes, swiveling and firing over the bar at his first attempt and curling his second wide of goal.
But he was not well-served by Sydney players who may take some time to learn how to work with a player of his quality. They failed to spot his well-timed runs early in the match and, lacking opportunities, Del Piero was forced to drop further and further back throughout the match to involve himself in play.
He later asked fans to be patient while he and his teammates got to know each other.
"I am not satisfied — we lost," Del Piero said. "But it was the first match. We need to do hard training, day by day, and think of the next game. After 10 matches, we can talk in general, but not now.
"I'm OK. I played 90 minutes but I need to do better. I need to improve. I'm enjoying it, but not for the result."
Heskey's A-League debut also ended in an upset defeat. The former Liverpool and Aston Villa striker had shots on goal in the 19th and 40th minutes and was subbed after 70 minutes, still acclimatizing after only 10 days in Australia.
Ono looked sharp when he came off the bench in Western Sydney's historic league debut against minor premiership-winners Central Coast. The Wanderers proved more than competitive as they stepped into the vacancy in the 10-team league left by the departure last season of Gold Coast.
"We got a result and showed we can compete at this level," Western Sydney coach Tony Popovic said. "We set ourselves high expectations, we said that we'd be very competitive on the first day that we took on this project and we had no doubt that we would be. So the performance the boys put in doesn't surprise anyone in our dressing room."
Melbourne Heart beat Melbourne Victory in the derby match that opened a league season that concludes in April after 27 rounds.
Perth beat defending champions Brisbane 1-0 in a reversal of the result of last year's grand final.