For nearly all 90 minutes of Monday's debate, it didn't seem like Hillary Clinton, the first female nominee of a major political party engaging in her first presidential debate, would have the chance to reference gender. But in his second-to-last question of the night, Lester Holt asked Donald Trump about his comments that Clinton "doesn't have a presidential look."

"She doesn’t have the look,” Trump responded. "She doesn’t have the stamina. I said that she doesn’t have the stamina and I don’t believe she has the stamina.”

Clinton was ready for the question. "Well, as soon as he travels to 112 countries and negotiates a peace deal, a cease-fire, a release of dissidents, an opening of new opportunities and nations around the world — or even spends 11 hours testifying in front of a congressional committee — he can talk to me about stamina,” she said.

"He tried to switch from looks to stamina,” Clinton continued. "This is a man who has called women pigs, slobs, and dogs."

Last week, Clinton campaign released a 30-second ad making a similar point. It shows 10 young women looking at themselves in mirrors as Trump's musings on women's bodies play in the background: "I'd look her right in that fat ugly face of hers ... She's a slob ... She ate like a pig ... A person who's flat-chested is very hard to be a 10 ... Does she have a good body? No. Does she have a fat [bleep]? Absolutely."

Since Friday, the ad has been played on YouTube nearly 4.5 million times.