Credit: Gregg DeGuire/FilmMagic

Knock, knock. Khloe Kardashian was at her home in Tarzana, Calif. when estranged husband Lamar Odom -- looking noticeably thin in recently revealed photos -- dropped by on the afternoon of Tuesday, Oct. 1. A source close to Kardashian, 29, explains that Odom's visit was not planned -- but the embattled couple, who spent their fourth wedding anniversary Sept. 27 apart, sat down for a long talk.

"He was there for a couple of hours and they spoke," the insider explains. "They talked for a while, and he left." The meeting, in fact, isn't out of the ordinary for Kardashian and the NBA free agent, 33, who have been living apart for months but have seen each other from time to time.

Despite the meeting, a reconciliation does not seem likely for the once rock-solid pair, whose bond has been broken by Odom's infidelity and ongoing drug use. In fact, on their anniversary itself, another pal says, Kardashian called up Odom to warn him that she plans to file for divorce soon. "She wanted to give him fair warning," the pal explains.

"Khloe was very firm," the friend continues. "She think it's best they both move on."

Read more about Khloe and Lamar's marriage trouble in the new issue of Us Weekly, on stands now.