And that could be beneficial to Clinton, whose polling lead over Trump has fallen well within the margin of error since August, when her numbers skyrocketed following the Democratic National Convention.
CNN's instant poll to determine the winner of the debate gave Clinton a massive edge, with 62% of respondents saying she won as opposed to 27% who said Trump won.
Nate Silver, the polling guru and founder of the data-driven news site FiveThirtyEight, said Clinton's big win in that instant poll could give her a 2% to 4% bounce in the polls, if history is any indicator.
Even more problematic for Trump is that his second-day spin forced the narrative to stay on his worst lines of the night — including the final few minutes of the debate in which he defended his past attacks on women like comedian Rosie O'Donnell, who he said "deserved" the sexist insults he's thrown her way.
On Fox & Friends Tuesday morning, Trump fat shamed former Miss Universe winner Alicia Machado, saying she was the "worst" because she "gained a massive amount of weight" after winning the contest.
Clinton mentioned Machado at the debate, saying Trump's attacks on her weight were an example of his contempt for women.
It's a line that could motivate suburban women — a key demographic with which Trump needs to make inroads — to back Clinton in the fall.
Similarly, his instinct to attack Machado is reminiscent of his attacks on the Khans — the Gold Star family whose forceful rebuke of Trump at the DNC became one of the most memorable moments of the campaign so far.
Trump's response to the Khans likely explained, in part, why Clinton built a large polling lead in August.
To be sure, however, there is still more than a month to go before Election Day — an eternity in politics.
And there are two more debates on the calendar between Clinton and Trump, which gives Trump two more opportunities to turn Monday night's debate performance around.
Others are also pointing to the fact that in 2012, Mitt Romney was declared the winner of the first debate, but went on to lose to President Barack Obama in the fall — implying that Clinton's first debate win wasn't necessarily the silver bullet she needed to win in November.
Yet Romney — like Trump — never held a lead in the national polling average.
And Trump's own campaign surrogates, including former New York City Mayor Rudy Giuliani, are telegraphing that Trump could sit the other two debates out.
As she boarded her plane Tuesday morning, Clinton shrugged off the possibility that Trump might not debate, and even got in another zinger on Trump — who in television interviews Tuesday morning in part blamed the microphones for his poor performance.
"Anybody who's complaining about the microphone is not having a good night," Clinton said in response.