Testifying on Tuesday in Ellen Pao's discrimination suit against Kleiner Perkins, partner John Doerr said Pao and Trae Vassallo, another former partner, "had an explosion" outside his office.
Pao and Vassallo made complaints of discrimination and gender harassment, respectively, while at Kleiner.
Doerr said he couldn't hear what the argument was about, but asked Pao to write him a "confidential" letter outlining her grievances with Vassallo.
Pao alleged she couldn't depend on Vassallo to perform tasks she signed up for and had to ask repeatedly to get things done.
Pao also accused Vassallo of being "very competitive and defensive" and said she didn't share information with her.
Doerr agreed that Vassallo is a competitive person.
Pao's argument with Vassallo was used to bolster Kleiner's assertion that she needed to improve on her interpersonal skills, a comment which reappeared on her performance reviews.
"You need to create trusting relationships with all partners," said Doerr in one of Pao's reviews. "The top priority is to built a relationship of trust and cordiality - even fellowship - with Trae."