The "This Is Us" star was being interviewed during the red carpet for the Golden Globes when the hosts tried to transition to their other set of hosts, who were with Brie.
"Do you know a girl named Alison Brie?" Metz was asked.
She responded "Do I?" with a bit of an attitude and made a face as they cut away.
With the camera now away from Metz, she could still be heard on the mic, allegedly saying, "She's such a bitch."
It's unclear if the "GLOW" star — who is nominated for best actress in a musical or comedy — heard the remark.
But Metz seemed to say afterward that she did not say it, tweeting, "It’s terribly unfortunate anyone would think much less run a story that was completely fabricated! I adore Alison and would never say a bad word about her, or anyone! I sure hope she knows my heart."
A Vanity Fair reporter said she asked Brie about the incident, who seemed puzzled by the whole thing.
"Just asked Alison Brie about this," Nicole Sperling tweeted. "She had not heard about Metz’s comments and seemed very confused by the entire matter. 'But wh'?,' she asked. “I know her. I saw her on the carpet and I told her how beautiful she looked.'"
Metz and Brie aren't known to be enemies (or BFFs, for that matter) but the two did pose together at last year's Screen Actors Guild Awards.