According to the report, two NBA lawyers, one of whom was David Anders, went to the law office of Mac Nehoray on Monday afternoon for the purpose of authenticating the audio.
Nehoray is the attorney for V. Stiviano, the woman Sterling is purported to be speaking with on the recording. She also was present at the meeting Monday, TMZ Sports said.
The website shows two videos of people leaving the office after the meeting -- one featuring the two NBA lawyers and the other of Stiviano, with a visor pulled down to cover her face, with two other men. No one had any comments.
But TMZ Sports says everyone present had "NO doubt" that Sterling is the man on the recording, after listening to the 15 minutes that were made public.
The site is also reporting that sources who have heard the entire hourlong recording say Sterling absolutely knew he was being recorded. TMZ Sports has reported Stiviano has said she has more than 100 hours of recorded conversations with the 80-year-old Sterling, who is said to have used the tapes to refresh his memory because he frequently forgot what he said.
NBA Commissioner Adam Silver is expected to announce the league's findings at 11 a.m. PDT Tuesday.