Live 8 organiser Bob Geldof has urged Italian stars to join its Rome concert, after the headline act pulled out and another singer proved hesitant.
Geldof told Italian stars it would be "the biggest concert of your life"
Rock star Vasco Rossi pulled out of the 2 July concert, saying it clashed with another gig, while Lorenzo Jovanotti asked for more details before joining.
But Geldof said Italian stars should not hesitate to take part in "the biggest concert of your life".
Bryan Adams and Deep Purple were revealed among Canada's Live 8 line-up.
Celine Dion will perform by satellite in the multi-artist concert near Barrie, Ontario.
The Rome and Ontario concerts are among 10 global Live 8 concerts in cities including London, Philadelphia and Johannesburg aiming to highlight world poverty on 2 July, ahead of the G8 summit in Scotland.
They will be supported by a further concert in Edinburgh on 6 July, the first day of the summit.
Unlike in the UK, where Live 8 has received extensive publicity, it has been barely mentioned by the Italian media.
Popular Italian singer Vasco Rossi pulled out of Rome's Circus Maximus concert, saying it clashed with a gig he was due to play in Ancona, on the other side of the Italian peninsula.
Bryan Adams will be one of the biggest acts at Canada's concert
"Vasco is a great star, a really great, great artist, and I think he should be on that stage," Geldof told a news conference in Rome.
"Where's Vasco? Vasco where are you? We want Vasco. We need Vasco," he added.
Singer Lorenzo Jovanotti, another household name in Italian pop, said he would not agree to play Live 8 until he received more information about the Rome concert.
Geldof said he would speak to Jovanotti personally. US stars Faith Hill and Tim McGraw and Italian singer Zucchero were among acts confirmed for the Rome concert so far.
The Ontario concert will be hosted by comedians Dan Akroyd and Tom Green, and will also feature Motley Crue, The Barenaked Ladies, Gordon Lightfoot, Our Lady Peace and Les Trois Accords among others.
Meanwhile U2 singer Bono - who is due to perform with U2 at Live 8's London concert - hailed "the charity of the old Live Aid" and "the justice of the new Live 8" at a Glasgow gig on Tuesday.