The freshman Florida senator — who to date has pursued a sleeper strategy, working not to leap out ahead of a crowded, turbulent field too soon — grabbed the spotlight in CNBC’s otherwise messy event. Billed on an economic theme, the third GOP debate turned as much into a confrontation between the financial networks’ moderators and the candidates as a contest among the Republicans themselves to articulate their governing visions.

Texas Sen. Ted Cruz, who likely placed among the top finishers, kicked off the media-baiting with an extended attack on questions he called shallow. And New Jersey Gov. Chris Christie likewise earned a fresh look from voters by embracing a posture more common from somebody with stronger polling—redirecting questions meant to highlight his differences from fellow Republicans to contrast the entire field with Democrats instead.

But Rubio set the tone for the night in the opening minutes of the debate, parrying an attack by Bush on his absenteeism in the Senate. A CNBC moderator prompted the exchange by asking Rubio about a Florida newspaper editorial calling for his resignation while he pursues the presidency. Bush jumped in with a prepared attack, telling Rubio he should start showing up for Senate votes “or let someone else take the job.” But Rubio was clearly ready, firing back that Bush was only going after him because “someone has convinced you that attacking me is going to help you…. Here’s the bottom line. My campaign is going to be about the future of America. It’s not going to be about attacking anyone else on this stage.”

Bush looked small, and he never quite recovered. Rubio’s jujitsu on his vanishing Senate attendance may prove insufficient for voters. But in the primordial language of that eye-to-eye standoff, he emerged as the alpha. The confrontation was particularly bracing, considering the backstory: These men have been close colleagues and even friends. They’re also locked in a two-way contest to wear the establishment crown that has traditionally conferred the nomination. Their exchange on Wednesday could soon prove the major inflection point. And with establishment backers raising alarms about the staying power of the outsider candidates, the moment could hardly be more propitious.

Meanwhile, the trio of outsider candidates — Donald Trump, Ben Carson, and Carly Fiorina, who’ve shared roughly half the polling support in the race so far — failed to make much of an impression on the stage at the University of Colorado Boulder.

Trump, slipping against Carson in Iowa but still leading nationally, demonstrated some of his signature feistiness early on by lacing into Ohio Gov. John Kasich for criticizing his platform. Kasich made a splash on the stump this week by declaring himself exasperated with the “hysterical” and “ridiculous” policies of rivals he didn’t name while clearly implicating Trump and Carson. After Kasich re-upped the critique at the debate, Trump pounced, calling him a “managing director at Lehman Brothers when it went down the tubes…. He was such a nice guy and he said, ‘Oh I’m never going to attack,’ but his poll numbers tanked—that’s why he’s on the end—and he got nasty. So you know what? You can have him.”

But from then on, besides mixing it up with the moderators a few times, Trump proved uncharacteristically quiet. Rubio filled the vacuum, weaving his up-from-bootstraps biography into sales pitches for his tax, entitlement, and immigration reform proposals. And he got in a few licks of his own on the evening’s favorite punching bag. Interrupting a discussion about the role of free-spending outside groups in the campaign, he said, “You know, the Democrats have the ultimate Super PAC. It’s called the mainstream media.”