Melbourne Victory may be facing a please explain from FFA after a tweet from the club's official account appeared to criticise referee Peter Green during the club's Big Blue loss.
The tweet, published early in the second half, read: "COMPETITION: Who wants to be (referee) Peter Green's + 1 to Del Piero's 39th birthday party tonight?"
The Italian superstar, whose birthday fell on match day, won and scored the penalty that proved the decisive goal in a pulsating Big Blue showdown at Allianz Stadium.
Del Piero was also awarded a number of free kicks after conning rivals into fouling him, using every inch of his experience.
The Victory tweet treads a fine line between humour and bringing the game into disrepute, although the club is unlikely to be punished.
"It will be looked at like most things from a round of football and they may be given a warning to be careful what they write in future," a FFA spokesman told Sportal.
Victory players and coaching staff were clearly frustrated at some of Green's decisions, with coach Kevin Muscat and Del Piero appearing to exchange words at one stage.
Asked after the match if he was frustrated by the number of free kicks awarded Del Piero, Muscat paused for several seconds before replying: "You guys were here so you can report about it. I don't want to get involved."
Muscat was just as angry with his side's inability to kill off a Sydney side playing with 10-man for more than an hour.
Victory recovered from a 2-0 deficit to draw level before falling behind again and squandering several second half chances.
Muscat said: "We've conceded three goals from set pieces and that leaves you with a mountain to climb.
"We carved out a few chances but it's hard when they had every man behind the ball.
"We asked for patience, and to wait for the right time, but we just couldn't finish the chances we had.
"Credit to Sydney, but from our perspective it was a disappointing night."
Sydney coach Frank Farina, meanwhile, does not expect the heat on him or the club to subside despite the Sky Blues' courageous win.
The hosts played a man down for 65 minutes after losing defender Marc Warren to a red card but dug deep to end a three-match losing streak that had Farina in the sight of critics.
But the coach has been around long enough – and is enough of a realist – to know the pressure will not ease after just one win.
"With us we've got to win every week – that's the expectation otherwise people get on our backs," Farina said.
"This is a big club, it's Sydney FC, and next week's the same. We'll go in with an attitude it's a must-win game."
Sydney's breakthrough win was achieved the hard way in a pulsating Big Blue that ebbed and flowed for 90 minutes.
Asked if 'relief' was the best way to describe his emotions, Farina replied: "No, more satisfaction.
"People don't understand my make-up. I don't let things get to me because if you do that and show you're under pressure it goes on to your team.
"We're a team. We win together and we lose together.
"They did the club proud."
Midfielder Nicky Carle added: "We needed to really dig deep and I feel the graft and the team effort got us over the line.
"It's not about being pretty, it was about rolling your sleeves up and making sure we put in the effort.
"We can go from this. It gives us some confidence."
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