Only Donald Trump could still dominate a debate without even showing up. His decision to boycott the final debate in Iowa roiled the Republican field - and soak up a few more precious news cycles before voters caucus on Monday. Here's what we're watching ahead of Thursday's 9 p.m. debate on Fox News:

Trump Trump Trump. The billionaire developer is holding a rival event across town to benefit wounded veterans after Fox News refused to cede to his demands that it drop Megyn Kelly as a moderator for the night's debate. Trump has remained atop the national polls despite some tepid performances, and skipping this one will deprive Texas Sen. Ted Cruz - neck-and-neck with Trump in Iowa polls - of a last chance to assail him in person. But Trump's no-show could also blow up in his face by alienating Iowans who want a final glimpse of the top contenders on the same stage. And there's always a chance he can stun the crowd - and his rivals - with a late arrival. "Surprise them - show up," counseled former New York Mayor Rudy Giuliani.

Can Ted Cruz exploit a Trump no-show? There's a reason Cruz challenged Trump to a one-on-one duel after the billionaire backed out of tonight's debate: He's been slipping in the Iowa polls lately amid criticism that his strategy to hit all 99 counties in the state is costing him votes by keeping him from major population centers. Cruz has stepped up his pitch for the evangelical voters that dominate the GOP electorate by stumping around the state with commentator Glenn Beck. Can he make the most of a Trump-less stage to make a final debate pitch to conservatives?

Marco Rubio tries to ride a wave. The polls and pundits agree Iowa comes down to a two-way race between Cruz and Trump. But Florida Sen. Marco Rubio is working to convince Iowans who spurn both of those anti-establishment candidates to rally around him as the mainstream choice. He's racked up a string of recent endorsements - including a hat-tip from Iowa Sen. Joni Ernst - and his town halls are hosting growing crowds. Watch closely as he tries, again, to position himself as the establishment's pick.

The other guys. Retired neurosurgeon Ben Carson has plummeted in the national standings after a series of foreign policy flubs, but he's still in fourth place in most Iowa polls. That puts a giant target on his back for all the other contenders looking to make up lost ground in the final days. And Kentucky Sen. Rand Paul will rejoin the main stage after boycotting the last GOP showdown when his poor poll numbers relegated him to a lower-profile time slot. He's already looking to shake things up, declaring that the "IQ of the debate went up" when Trump opted out.

New Hampshire is calling. Then there are the candidates who have already locked in on the Granite State, where voters cast their ballots on Feb. 9. New Jersey Gov. Chris Christie and Ohio Gov. John Kasich have staked their presidential bids on the New Hampshire primary, and both could tailor their message tonight to the independent voters that hold sway in the state. And former Florida Gov. Jeb Bush, near the bottom of most national polls, is still waiting for a breakout moment to challenge Rubio and the other mainstream candidates for the hearts of the GOP establishment.