Unlike Bersani, who fluffed his attempts to get a crowd response by replying for them - "Will we win or will they win? We will," he said before the audience had time to react - Renzi's timing was spot on.
Reminding Sicilians that Berlusconi took all of Sicily's 61 voting precincts in 2001, helping him to a landslide victory nationally, Renzi raised a roar from the crowd.
"We remember the 61-to-0 of this region. What did they do for Sicily?" he asked, to shouts of "Nothing!".
KINGMAKER
Sicily already swung back to the left last year, when an openly gay, mafia-bating leftist, Rosario Crocetta, won the regional elections, boding well for the PD when Italians vote on Sunday and Monday.
But if the PD does come first nationally, it is likely to have to govern in coalition with either Monti's centrist grouping or seek to persuade members of the upstart, anti-establishment 5-Star movement to support them.
Led by rabble-rousing comic Beppe Grillo, 5-Star scored 16 percent in an average of final polls published before a pre-election blackout, putting it third after the PD and Berlusconi's People of Freedom.
Potential kingmaker Grillo has ruled out joining a coalition with any of the parties, all of which he brands as dishonest. But that might not exclude the possibility of 5-Star lawmakers supporting a coalition from the outside, and Renzi aimed some of his speech at them and their electors.
"Let me confess, I'm going to out myself. I have been a mad fan of Grillo's shows for years," he said, adding that he also supported the comic's ideas on the environment, technology and reducing the cost of politics.
"There's just one thing. They can talk as much as they like, but they'll never do it, they'll never do it because a protest vote doesn't go anywhere," he said.
PD supporters in Palermo seemed keen on working with 5-Star.
"I think it's a positive movement. It has brought together a lot of people who are unhappy (with politics)," said Cecilia Marescalchi, a 59-year-old local council employee who said the PD had failed to reach the youth.
"Young people feel they are being heard by Grillo, they are attracted to him," she said, admitting that perhaps if the PD has chosen Renzi as their leader, rather than Bersani, it might be getting more of those votes lost to 5-Star.