Los Angeles, Dec 23 : 'Friends' star Lisa Kudrow gave her ex-boyfriend Conan O'Brien some unconventional encouragement when he was preparing to succeed David Letterman on NBC's 'Late Night', New York Post reported. As per Vanity Fair history of the first year of 'Late Night with Conan O'Brien', his then girlfriend, Kudrow (now 60), said, 'I don't know how much we talked about it. I just knew, 'You're trying to replace David Letterman." She had said, 'No one replaces David Letterman. You're no one." "It can't be anybody that an audience would know,' she said. As per New York Post, Letterman (76) helmed the show from 1982 to 1993 before moving from NBC to CBS to host 'The Late Show With David Letterman' from 1993 will his retirement in 2015. Conan, who led the show from September 1993 to February 2009, was unknown at the time when he started, which Kudrow tried to say was a good thing. According to Vanity Fair, NBC was also considering Gary Shandling, at the time. O'Brien confessed that there were a lot of growing pains along the way. He called his team 'very naive' and said that they 'just had to go through the spanking machine' to get the spot. /IANS