Donald Trump did everything he possibly could to throw Hillary Clinton off her game.

The Republican nominee for president came to bully his Democratic opponent and the moderator of the first debate of the fall campaign. He interrupted Clinton’s remarks constantly, aggressively, and obnoxiously. He sneered and shrugged and sniffled. He grimaced and grumbled. And then he interrupted some more.

There were points early in the 90-minute exchange when the debate appeared to be headed the way of the Republican forums that saw Trump roll over all those governors and senators on his way to the party nomination. Trump may not have spent much time preparing for the debate, but he was clearly prepared to badger his way to the bully pulpit from which he seeks to dominate every political interaction.

Then, as Trump was racing through an economic rant, moderator Lester Holt finally said: “Let me let Secretary Clinton get in here.”

Clinton calmly looked away from Trump and toward the tens of millions of American people who were watching the debate and offered a sobering history lesson.

“Well,” she said, “let’s stop for a second and remember where we were eight years ago. We had the worst financial crisis, the Great Recession, the worst since the 1930s. That was in large part because of tax policies that slashed taxes on the wealthy, failed to invest in the middle class, took their eyes off of Wall Street, and created a perfect storm.

“In fact, Donald was one of the people who rooted for the housing crisis. He said, back in 2006, ‘Gee, I hope it does collapse, because then I can go in and buy some and make some money.’ Well, it did collapse.”

Trump knew he was in trouble.

“That’s called business, by the way,” the billionaire said, interrupting once more.

Clinton paid him no attention. She kept talking to the voters she must win over in a race that has become too close for comfort.

“Nine million people—9 million people lost their jobs. Five million people lost their homes. And $13 trillion in family wealth was wiped out. Now we have come back from that abyss. And it has not been easy. So we’re now on the precipice of having a potentially much better economy, but the last thing we need to do is to go back to the policies that failed us in the first place,” said Clinton, who then pointed out that

Independent experts have looked at what I’ve proposed and looked at what Donald’s proposed, and basically they’ve said this, that if his tax plan, which would blow up the debt by over $5 trillion and would in some instances disadvantage middle-class families compared to the wealthy, were to go into effect, we would lose 3.5 million jobs and maybe have another recession.

They’ve looked at my plans and they’ve said, OK, if we can do this, and I intend to get it done, we will have 10 million more new jobs, because we will be making investments where we can grow the economy. Take clean energy. Some country is going to be the clean-energy superpower of the 21st century. Donald thinks that climate change is a hoax perpetrated by the Chinese. I think it’s real.

Trump knew he was in even more trouble.

“I did not. I did not. I do not say that,” he stammered.

Clinton was not being interrupted this time.

“I think science is real…,” she said.

“I do not say that,” Trump interrupted urgently, but ineffectually.

Clinton was not paying attention to him. She was on a roll.

“And I think it’s important that we grip this and deal with it, both at home and abroad. And here’s what we can do. We can deploy a half a billion more solar panels. We can have enough clean energy to power every home. We can build a new modern electric grid. That’s a lot of jobs; that’s a lot of new economic activity,” she said. “So I’ve tried to be very specific about what we can and should do, and I am determined that we’re going to get the economy really moving again, building on the progress we’ve made over the last eight years, but never going back to what got us in trouble in the first place.”

Clinton had delivered her message at a critical early point in the most critical debate. And she continued to do so throughout the remainder of the evening—as the dialogue turned to Trump’s undisclosed tax returns and unpaid bills, his divisive response to racial justice and policing issues, his birther fantasies and his unsteady approach to matters of war and peace.

Trump kept interrupting and grimacing and grumbling and sniffing.

But it was the billionaire, not the former senator and secretary of state, who was off his game. He wasted critical stretches of the night urging reporters to call Sean Hannity, hating on Rosie O’Donnell, ruminating about 400-pound bloggers, and bragging that the Trumps had settled racial-discrimination lawsuits “with no admission of guilt. Zero.”

Trump could not get his groove back. Where he should have been prepared for attacks—on his failure to pay taxes, his failure to pay contractors, his scheming to profit off the economic meltdown of 2008—Trump fell back on glib one-liners, frequently bragging that he was “smart” or good at business when he engaged in actions that most Americans know to be wrong.

Clinton was ready, at every turn. When Trump tried to deflect blame for raising questions about Barack Obama’s place of birth, Clinton spoke warmly and well of the president. When Trump tried to argue for “stop-and-frisk” policies, Clinton spoke up for the US Constitution, for respect of all Americans, and for racial healing. When Trump suggested that she lacked stamina, she welcomed the opportunity to recite her résumé and record of accomplishment.

At one point, the Republican seemed to criticize Clinton for preparing for the debate.

The Democrat seized on the opening with absolute delight.

“I think Donald just criticized me for preparing for this debate. And yes, I did,” said Clinton. “And you know what else I prepared for? I prepared to be president. And I think that’s a good thing.”

Boom!

That was a winning line on what for Hillary Clinton was a winning night.