Tonight's main event takes place in Des Moines, Iowa and Thursday's face off takes place in Sioux City. Both have the potential to be more like "fight night" than debate, as candidates make their case to caucusgoers and the nation.
The debate airs at 9 PM PT on ABC News.
Here are some things to watch for tonight.
1. Can Newt take a punch?
2. Will Mitt land a punch?
3. How hard will Ron swing?
4. Can Rick recover?
5. Will Michele and Rick get in the ring?