To better understand what happened at Saturday night's GOP debate, let's go back a few months to Republicans' October debate on CNBC.

In one of his break-out moments this campaign, Sen. Marco Rubio (R-Fla.) slammed down an attempted jab from his former mentor, former Florida governor Jeb Bush (R), about Rubio's Senate attendance record.

"The only reason why you're doing it now is because we're running for the same position, and someone convinced you that attacking me is going to help you," he said.

It was a devastating attack in part because Rubio delivered it with conviction, catching Bush off-guard and challenging his once-mentor's own conviction — both for the game of politics and for the job both men ultimately want.

On Saturday, New Jersey Gov. Chris Christie turned the tables on Rubio with his own bruising and personal line about depending too much on advisers and talking points.

The line, like Bush in that October debate, appeared to catch Rubio off-guard. And, like the moment was for Bush, the exchange was a potential game-changer for Rubio — and not in a good way.

Here's the play by play:

Earlier this week, Rubio's supporter, former Pennsylvania senator Rick Santorum, struggled in a TV interview to name a Rubio accomplishment. So on Saturday, ABC gave Rubio a chance to defend his record.

Rubio said leadership shouldn't be about time spent in office — if it were, then someone like Vice President Biden would be president, he said.

Over to the side of the stage, Christie saw an opening for the playbook he's followed in most of these debates: Bash the senators as Washington show horses who don't know what true leadership is.

Christie launched into a lecture about what leadership is, comparing Rubio to another young, talented first-term senator who ran — and won — in 2008.

"He simply does not have the experience to be the president of the United States and make these decisions," Christie said.

Rubio shot back with a line about how New Jersey's credit rating had been downgraded under Christie. Then, he somewhat awkwardly pivoted to his stump speech about how Barack Obama is ruining this nation, and how he will make America great again.

It was a scripted moment from a seemingly November-focused Rubio. And Christie called him out on it:

Rubio tried to get personal by accusing Christie of not wanting to return to New Jersey during a recent snowstorm. The crowd saw what Rubio was doing and booed.

As the two bickered back and forth, Rubio seemed stuck in one gear: Repeat his stump speech. And every time, Christie called him out on it.

"There it is," Christie said, turning toward the audience. "The 25-second memorized speech."

In fact, Rubio seemed stuck during this exchange on the same talking points Christie accused him of clinging to. He had a strong third place finish in Iowa, nearly coming in second, and has been gaining ground in the polls ahead of Tuesday's New Hampshire primary. A strong finish in the state would help make Rubio's case that he's the establishment candidate the rest should rally behind.

But he seemed almost too eager to make that case in Saturday's debate. And perhaps as a result, his debate performance sounded more like a broken record than the establishment leader. It did him no favors that Christie, a talented debater, seized the moment to paint Rubio as just another scripted Washington insider.

For Christie, who has lagged in the polls and needs a strong finish in New Hampshire as well, it was the dream scenario: Have a break-out moment and knock down the guy ahead of him in the process.

We'll have to wait until Tuesday to see who really came out on top of the brawl.