Nellie Andreeva

Two decades after the Jay Leno-David Letterman battle for The Tonight Show, the Tonight Show curse has struck again with yet another messy host transition. In 1992, NBC had two hot young comedians eager to replace longtime Tonight host Johnny Carson, Leno and Letterman. The network chose Leno and created a formidable late-night rival in Letterman, who defected to CBS to launch The Late Show. Leno and Letterman had been going at each other ever since, looking to outrate and outlast each other. Letterman had the upper hand in the ratings early on before Leno took the lead, holding onto it for the most of the past 17 years. The two even have been timing their contracts to end at the same time. They did it again this time, with Leno’s deal up in September 2014 and Letterman’s contract also going through late 2014.

Related: NBC Sets ‘Tonight Show’ Transition With Jimmy Fallon Taking Over In Spring 2014

NBC‘s announcement today that Leno will retire in spring (likely February) of 2014, assures that Letterman will be the last man standing in the duo’s 20-year rivalry. Having outlasted his archrival, 65-year-old Letterman too may decide to retire at the end of his deal instead of going toe-to-toe with younger new competitors, Jimmy Fallon (38) on NBC and Jimmy Kimmel (45) on ABC. The key thing is that it will likely be his decision to make. Letterman has largely been given carte blanche to do the show for as long as he wants to. (Though in his recent interview with Oprah, Letterman claimed he has an agreement with CBS topper Les Moonves that Moonves has to tell him when it is time to go.)

Meanwhile, fearful of turning another disgruntled NBC late-night host into a bitter rival at another network, NBC brass have been forcing a host transition by pushing Leno out despite his position as the top-rated late-night host. Twice. There was the botched 2009 passing the baton to Conan O’Brien, which NBC’s Jeff Zucker had committed to five years in advance, ordering Leno into retirement before he was ready to leave. If Leno (62), who was reinstated as Tonight Show host eight months later, was hoping for a more dignified exit the second time around, he didn’t quite get it. As speculation about him being replaced by Fallon escalated, Leno went mercilessly after NBC on his show, berating the network over its woeful ratings. That triggered a pointed email from NBC chairman Robert Greenblatt, leading to a heated exchange between the two and a new wave of loaded on-screen barbs at NBC and its executives and shots from other comedians, including Jon Stewart.

Greenblatt and Leno have since buried the hatchet but, with the situation and its portrayal in the press getting out of hand, NBCUniversal CEO Steve Burke personally intervened to smooth things over. He flew over to Los Angeles late last month for a sitdown with Leno and his executive producer Debbie Vickers. According to people familiar with the matter, Burke laid out different scenarios for Leno to consider. From what I hear, none of them involved Leno staying beyond the end of his contract, meaning that the network forced Leno to retire for a second time instead of giving him a chance to make and announce that decision on his own and via his own timetable. Letterman’s relationship with CBS also has been bumpy, reaching a low point in 2002 when the comedian contemplated a move to ABC. But he eventually patched things up with Moonves, whom he used to mock relentlessly on the show early on. Letterman also seems to have made peace with Leno. He sounded sincere on the Late Show today, congratulating his rival “on a job well done at the Tonight Show” and slamming NBC over its treatment of the veteran Tonight host. Nothing brings foes together like a common enemy…

A main difference between NBC and CBS’ late-night blocks is that at CBS, Letterman controls both the 11:30 PM and 12:30 AM shows, eliminating the danger of the 12:30 AM host to bolt, which has been a main driver in NBC’s rash decisions to push Leno out. If Lorne Michaels, who is taking over The Tonight Show With Jimmy Fallon, also holds onto Late Night or whatever its successor might be, that also is likely to help with future transitions. But that will be a problem for a future NBC regime — hat is if Leno goes away this time. As Letterman quipped today, addressing Leno, “congratulations on a nice long run there at the Tonight Show, if in fact you’re not coming back.”

TV Editor Nellie Andreeva - tip her here.

For all of Deadline's headlines, follow us @Deadline on Twitter.