Early elections scheduled for February were triggered after Mr Berlusconi (76) pulled his party's parliamentary support, prompting Mr Monti's resignation.
Since he announced his intentions to seek office again, Mr Berlusconi, accompanied by his beautiful new fiancee 50 years his junior, has hammered Mr Monti's pro-Europe rigour, saying it has inflicted pain and failed to improve the economy.
But Mr Monti, who is head of a centrist bloc on a pro-Europe reformist package, said: "Berlusconi has used unsuitable weapons against me... like family values. Which speaks for itself.
"I think ethical values are fundamental and need to be defended. I hate parties that make use of these ethical values, which they often do not respect in daily life, as a weapon against their rivals,"
Mr Berlusconi has been accused by prosecutors of paying for sexual intercourse with an alleged under-age prostitute, a charge he denies. His penchant for cavorting with young models and showgirls finally became too much for his wife Veronica Lario. According to a legal separation approved on Christmas Day, he has agreed to pay her €36m a year.
Mr Monti also defended his crackdown on tax evasion and staving off economic collapse, taking aim at Mr Berlusconi's logic. "First he says that the government has been a disaster, then that it did everything it could. I hope voters are less confused then me," Mr Monti said.
Mr Berlusconi countered by saying that Mr Monti (69) was "no longer credible", claiming he "broke his word" by entering the race after promising he would not when he took over in November 2011.
Last year, Mr Monti, an economics professor, pushed through austerity reforms as Mr Berlusconi sat on the sidelines.
Though markets are calm, lending is still tight, Italians are not spending and joblessness keeps rising. A new wave of taxes take effect this year on everything from utilities to gas and postage stamps.
But Mr Monti insisted better times lie ahead, saying he would cut labour taxes to spur growth and redistribute wealth.
"The light at the end of the tunnel is closer than before and I am far more optimistic that the tunnel will not collapse and destroy us as it threatened to do," he said.
Mr Monti's coalition is in a three-way race with the leading Democratic Party (PD) on the left and Mr Berlusconi's People of Freedom (PDL) on the right. (© Daily Telegraph, London)