(AP) -- It was the final opportunity for Donald Trump's opponents to change the trajectory of the Republican presidential race before Super Tuesday, and they made the most of it.

The billionaire businessman was positioned at center stage on Thursday night at the GOP debate in Texas as the undisputed front-runner for his party's nomination, having won three consecutive primary contests.

His leading competitors, first-term Sens. Marco Rubio and Ted Cruz, sought to score a game-changing moment heading into a series of critical March 1 primary contests. Ohio Gov. John Kasich hoped to prove he and his optimistic message have a place in the race, while retired neurosurgeon Ben Carson was just trying to get a word in.

Here are the top takeaways from Thursday's high-stakes debate:

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TRUMP UNDER FIRE

It took 10 debates, but Trump finally took fire from all of his leading rivals on national television.

The former reality television star was on his heels for extended stretches as Rubio and Cruz attacked him from either side of his place at center stage. They went after his business record, his personal wealth, a "fake" university that bears his name, his commitment to conservative social issues, his financial donations to Democrats and his lack of specifics on major policies.

Trump was clearly irritated at times, lashing out at his opponents and moderators alike. "Are you going to ask anybody else a question?" an agitated Trump asked at one point.

It was often not the picture of strength that Trump has portrayed for virtually the entire 2016 Republican primary season.

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RUBIO OUTSHINES CRUZ IN ATTACK-DOG ROLE

Marco Rubio wanted to come out as the strongest alternative to Trump on Thursday night. He largely succeeded.

The freshman senator from Florida set the tone early and delivered the quote of the night when he attacked the source of the billionaire businessman's wealth: "If he hadn't inherited $200 million, you know where Donald Trump would be right now? Selling watches in Manhattan," Rubio charged.

Cruz joined the fight against Trump, but was outshined consistently by Rubio, who responded to the urgency of the moment with Super Tuesday less than a week away.

While both Rubio and Cruz were effective, it was notable that Rubio bested his senate colleague on Cruz's home turf. Cruz is coming off three consecutive third-place finishes and could be forced out of the race if he loses to Trump in his home state of Texas on March 1.

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MAKE AMERICA GREAT AGAIN, BUT HOW?

Trump has won three consecutive primary contests by promising to "make America great again" -- without saying how he'd go about it in much detail. And the Republican front-runner struggled Thursday night when pressed for those details -- especially on health care.

Pushed by his competitors and the moderators to explain how he would replace President Barack Obama's signature federal health-care law, Trump repeated his call to allow people to buy health insurance across state lines.

"What else is part of your plan?" Rubio asked as Trump offered the same answer. "Now he's repeating himself," Rubio went on, coyly referencing a previous debate in which Rubio badly hurt himself by repeating the same answer several times.

Given a final opportunity by the moderator to explain another way he'd replace the federal health care law, Trump offered only, "There's nothing to add."

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WHAT ABOUT ME?

Kasich and Carson were ignored for long stretches of Thursday's debate, but each made their mark at times -- albeit in very different ways.

The Ohio governor was stubbornly optimistic throughout the evening and refused to attack his rivals even in the midst of the most heated exchanges. "We have to stop this," Kasich said at one point as the moderators briefly lost control. "Let's start solving problems," he said during an extended pointed exchange on immigration.

Carson, a retired neurosurgeon, stood out briefly during the health care discussion, but seemed to acknowledge his own weak standing after finishing in last in two of the past three primary contests.

"Can somebody attack me please?" he asked at one point. His rivals ignored the request.

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TOO LITTLE TOO LATE?

Even if Thursday's debate performance dents Trump's momentum, it could be too little, too late, to loosen his tightening grasp on the Republican presidential nomination.

Unfortunately for Trump's critics -- and there are many in the Republican Party -- his main rivals waited until five days before Super Tuesday to attack him so aggressively in a debate.

Trump has a big lead in the early delegate count, and preference polls suggest he's well positioned to add to it next week.

"I've dealt with much tougher," Trump told CNN moments after the debate ended. "I really enjoyed it."

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Peoples reported from Atlanta.

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Follow Steve Peoples on Twitter at: http://twitter.com/sppeoples