If you face a drunk driving or OWI charge in Wisconsin and you have prior OWI conviction that the state intends to use against you in the current prosecution, what is the best way to challenge them?

What does the government have to prove in regards to your prior DUI charge or record if you don't just admit that the record is true? Are you entitled to a jury trial on the issue of whether you have prior convictions and/or whether those prior convictions are legitimate?