Hillary Clinton was "discombobulated" by Donald Trump standing behind her at the second presidential debate in October, the former Democratic candidate acknowledged in an interview to promote her new book.

"It was so discombobulating," Clinton in an interview that will be aired on CBS this Sunday.

In her forthcoming narrative of the election, "What Happened," Clinton reviews how she lost to Trump. In Sunday's interview, she pointed to that moment, one that attracted significant social media attention at the time, as a possible instance in which she may have missed an opportunity. The former secretary of state has been criticized for shunting blame for her lost to other people and outside circumstances.

While she described Trump as a "creep" for stalking behind her onstage at the St. Louis debate while she tried to answer an audience question, Clinton acknowledged that she wasn't sure how to respond.

PREVIEW: Hillary Clinton describes uncomfortable, "discombobulating" moment with Trump during presidential debate; watch @CBSSunday on 9/10 pic.twitter.com/XK9czA61U1 — CBS News (@CBSNews) September 8, 2017

Ultimately, she opted to ignore Trump rather than confront him, a split-second decision she now questions.

Her "composure," she said, has equipped her well for serving in the public eye and staying steady and predictable. "But I think in this time we are in, particularly in this campaign, you know, maybe I missed a few chances," she said.