"I thought I'd wait a couple of days before I expose her business failure," Trump said. "But honestly, it's so ridiculous."
Halyna Sorensen's question during a town hall-style event that drew 3,000 people was too perfect for Trump to turn down, sending Trump spiraling into the latest iteration of his criticism of Fiorina's controversial business record -- not just at Hewlett-Packard, but at a lesser-known technology company called Lucent.
Sorensen, 66, was a Lucent employee when Fiorina took over a division of that company. And soon after Fiorina took over, Sorensen said she was forced to retire as part of changes Fiorina instituted.
Sorensen accused Fiorina of mismanaging the company, sending stock prices tumbling and, with it, taking nearly $500,000 Sorensen said she had invested as part of a retirement plan.
"She put our company Lucent Technologies in the ground," Sorensen said at the event in Rochester.
Trump perked up: "Carly Fiorina -- say it again -- people might as well hear it. I mean people have to learn."
"Go ahead, tell me," Trump said.
During Fiorina's tenure, the company overextended itself, reportedly "making big loans to sketchy customers," according to a 2010 Fortune magazine story
that examined Fiorina's record at the tech firm. The result: stock prices plunged.
The exchange came less than 24 hours after Trump and Fiorina sparred on the opposite side of the country, knocking each other's business records during CNN's Republican debate at the Ronald Reagan Presidential Library in California.
When asked why he couldn't hold back as Fiorina's record came up during the debate, Trump told CNN that record is an important issue voters should know about.
"You have to know about her past," Trump told CNN of Fiorina after the event. "Her past is terrible. She can't be elected."
Fiorina's camp did not respond to a CNN request for comment about her record as a Lucent executive in the late 1990s.
Fiorina emerged as the standout candidate from the debate, seizing her best moments at Trump's expense, most notably when she tweaked Trump over his disparaging comments about her looks, which he suggested in a Rolling Stone magazine article make her unelectable.
"I think women all over this country heard very clearly what Mr. Trump said," Fiorina said to overwhelming applause.
Voters can expect more fireworks between the two GOP candidates as Trump has emerged as Fiorina's fiercest critic -- repeatedly bringing up Fiorina's business record in recent weeks -- while Fiorina has not hesitated to take on the front-runner.
They will also have to duke it out as voters looking for a candidate with outsider appeal are drawn to both, neither of which have held elected office. And while retired neurosurgeon Ben Carson has surged to the No. 2 spot off Trump's outsider appeal, Fiorina's debate performance may see her rise in the polls to become a real challenger and potential threat to Trump.
For Sorensen, that's not an option.
"When (Trump) says something he does it. He walks the talk. He doesn't just say it and forget about it. Carly Fiorina, she's a 'yes' person," Sorensen said. "Carly Fiorina is a waste of breath."