**Want FOX News First in your inbox every day? Sign up here.**

NORTH CHARLESTON, S.C. – You could still say the race was wide open, but after Thursday’s debate, that would be a lie.

The Fox Business Network’s faceoff offered a hopeful glimmer for Republicans wondering when they will get past the preliminaries and on to the business of picking a presidential nominee.

This long-running television show is about to see a spinoff. Call it “The Contenders.”

It won’t happen all at once, but the trio of Donald Trump, Ted Cruz and Marco Rubio stood far enough above the rest of the field here that you could, for the first time, really sense the separation of the two tiers on the debate stage.

This happened much earlier in the previous presidential cycle, in which there had already been 13 debates by this point, instead of six. But after a late start and five months of slow going, the debates are beginning to do their job: To reveal for GOP voters the strengths and weaknesses of their candidates.

Part of the frustration for anyone watching the prior debates was that no one was both willing and able to take on frontrunner Trump directly. Some combination of calculation, cowardice and incompetence had kept the whole field iced against the guy who polls say is walking away with their nomination.

The race had a frontrunner who for months was treated like a marginal candidate on debate stages. While seventh- and eighth-place cellar dwellers raged at each other and drew approving pundit nods, Trump was left alone at center stage pulling faces and rolling his eyes.

But finally, finally, finally Cruz treated Trump like a serious candidate. And Cruz did what any Texan would do if you called him a Canadian: He fought. And for the first time, someone actually bested Trump in a head-to-head showdown. It was a seismic shift in the race if only because it proved that it was even possible.

But it was more than that. It was Cruz’s announcement of his arrival as a real contender.

When Trump got tripped up and admitted that his Canadian birtherism was, in fact, motivated by Cruz’s rising stature in the race, it was the first clean, clear defeat Trump had taken on stage to another candidate. Cruz flipped a negative into a positive, and that’s the highest art in all politics.

But just about the time Cruz was getting cocky, Trump not only came alive but delivered what was the single best answer of his debate career thus far. Cruz had laid it on way too thick in his answer about what he meant when he accused Trump of having “New York values.”

When Trump answered, he took everything you knew about him and threw it out on its ear. Trump spoke tenderly and so softly that the audience needed to lean in to hear him tell the story of 9/11 and reminded his now-rapt that “everybody in the world watched and everybody in the world loved New York and loved New Yorkers.” It was a grand slam.

We already knew that Trump could shout down or insult a rival. What we hadn’t seen him do on stage is show this kind of range in so doing. Trump has continued to improve as a debater and a candidate, and in this one answer was all the proof you need.

For Rubio, boffo debate performances are the norm. His mix of high energy and a broad grasp of issues is a lethal combination in this setting. In debates, like your high-school diver’s ed class, speed kills.

While one could argue that Rubio had one of his best showings so far, winning rounds with Cruz and others, what really made this debate different for Rubio was the obvious separation between him and the other four candidates on stage not named Trump or Cruz.

For the other four, each debate brings the promise that this time will be the breakout performance or that this time they will really get tough. Well, we’re pretty well out of this times with 17 days before the first contest starts. Rubio, on the other hand, started at good and has moved to great.

Now, this is not to say that things can’t change. Certainly a stunning victory in any of the four early states could vault someone other than the top three into contention. And the opposite is true. Any of the three is only a few bad days away from bottom-tier oblivion.

Despite a promising path to the nomination, Rubio’s position is the most precarious of the big three, mostly because he is the one in closest reach to the bottom quartet. If Rubio powers past them in Iowa and New Hampshire, we will be off into a three-way sprint. If one of the others can trip him up, Cruz and Trump might run away on their own.

This has been a trying primary season for Republicans so far: Too many candidates, too much noise and too few clear scenarios that put a strong candidate into the general election season.

After this debate, they can finally start to picture the world differently.

Chris Stirewalt is digital politics editor for Fox News. Want FOX News First in your inbox every day? Sign up here.

Chris Stirewalt joined Fox News Channel (FNC) in July of 2010 and serves as digital politics editor based in Washington, D.C.  Additionally, he authors the daily "Fox News First" political news note and hosts "Power Play," a feature video series, on FoxNews.com. Stirewalt makes frequent appearances on the network, including "The Kelly File," "Special Report with Bret Baier," and "Fox News Sunday with Chris Wallace."  He also provides expert political analysis for Fox News coverage of state, congressional and presidential elections.