A court in Milan has decided it is competent to hear Silvio Berlusconi's sex trial - a setback for the Italian prime minister, who wanted it moved.
Mr Berlusconi's lawyers had argued the case should be heard by a special tribunal for ministers in Rome.
He is accused of paying for sex with an under-aged prostitute, and abuse of power. He denies the charges.
The case has already opened in Milan and moving it would have meant starting again from scratch.
Mr Berlusconi claims the Milan court is biased against him.
This trial - known as the Ruby case after the stage name of the alleged prostitute, Karima El Mahroug - is one of four trials the prime minister is currently facing.
The other three are related to corruption allegations.
In the Ruby case, prosecutors say Mr Berlusconi paid for sex with Ms Mahroug, when she was aged 17.
Although frequenting prostitutes is not a crime in Italy, having sex with one under the age of 18 is an offence punishable by a prison sentence.
They both deny they had sex.
He is also accused of abuse of power, by seeking Ms Mahroug's release from police custody when she was detained in another case.