Jeremy Au Yong After 90 minutes of non-stop talk, it was perhaps body language that spoke loudest about how the first presidential debate between Mrs Hillary Clinton and Mr Donald Trump played out.

Mrs Clinton was all smiles as she made her way towards the rows of supporters to greet and chat with them. Her rival, meanwhile, stood on stage in a huddle with his family, only cracking a smile occasionally and waving to his section. Then he promptly left the building while Mrs Clinton was still mingling.

By all accounts, the Democratic presidential nominee had won the debate handily. And much of it came down to being better prepared.

The former secretary of state had spent much time in the weeks leading up to Monday night's debate rigorously studying her opponent's positions and even consulting psychologists to understand what makes him tick. She had a mock debate stage built and spent several nights conducting practice debates that took place at exactly the same time the real thing did.

Mr Trump, in contrast, wanted to stick to the shoot-from the-hip style that got him through the primary debates.

In many ways, the Republican candidate had entered the night with a simpler task. He just needed to convince voters that he had the temperament to be president. And for the first 20 minutes or so, he largely succeeded.

He started out soft-spoken and polite and did not launch any direct attacks on Mrs Clinton, even calling her "Secretary Clinton" while she called him "Donald". He also had a strong moment while portraying himself as a political outsider pitted against an establishment figure.

The Democrats believed during their preparations that Mr Trump would be most insecure about his image as a successful businessman and planned to provoke him with attacks on that front. But even they could not have anticipated how effective the strategy would be.

When talking about his failure to disclose his tax returns, Mrs Clinton mused about what his reasons for keeping mum might be: "First, maybe he's not as rich as he says he is. Second, maybe he's not as charitable as he claims to be."

From that point, Mr Trump's performance began to come unhinged. He interrupted Mrs Clinton persistently, gave rambling, confusing answers and went after every piece of bait she threw.

Said University of Georgia debate expert Edward Panetta: "Viewers who tuned in for the first half-hour probably left the debate with a positive impression of Donald Trump. Viewers who watched the full debate were left with the impression of a debater who was not able to sustain a set of coherent and full messages."

In the process of trying to explain himself on everything, Mr Trump lost sight of his core message. There was no further talk about being a political outsider. He hardly attacked Mrs Clinton on her e-mail scandal, did not bring up the issue of immigration, and not once did he mention the phrase "basket of deplorables". The phrase has been a key rallying cry for his base ever since Mrs Clinton described half of his supporters that way.

There were also some big moments for Mrs Clinton, who simply allowed Mr Trump to talk himself into a hole. As he rambled on incoherently about his now-debunked claim that he opposed the invasion of Iraq before it happened and that he put an end to doubts about President Barack Obama's birth place, Mrs Clinton held her tongue, only to unleash short one-liners once he was done.

"Well, just listen to what you heard," she said after his answer on Mr Obama's birth place.

Experts said these were acts of restraint and judgment that could only come with practice.

If there is one consolation for Mr Trump, it is that there was no knockout blow. For all his mistakes, he still came across as more restrained than in nearly all of his primary debates. On top of that, pundits noted that he has been declared the debate loser before only to find that it had minimal impact on the polls.

Election forecaster Nate Silver of the FiveThirtyEight website thinks Mrs Clinton will get a bounce from Monday's performance but is not taking it as a given. "If undecided and marginal voters were willing to shrug off Trump's performance, then perhaps they really are in the mood for the sort of change that Trump represents, his faults be damned," he wrote.