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Stephen Colbert has won another key battle in his late-night “war” with Jimmy Fallon: His CBS Late Show is now No. 1 this season among adult viewers under 50, the key demo group most attractive to advertisers. While Colbert has dominated in overall audience for close to two years now, Fallon’s Tonight Show has clung to an ever-shrinking lead in the demo. But per Nielsen data released Tuesday, Late Show is averaging 658,000 adult viewers under 50 in the TV season to date, just barely ahead of Tonight (656,000 or 657,000 viewers, depending on which network you ask).

Colbert has been edging toward dethroning Fallon in the demo since the new season started in September, mostly because his show does so much better in delayed viewing. But last week, interest in the midterm elections pushed Colbert to his first-ever weekly demo win among same-day audiences, thus allowing Late Show to pull ahead in the season-to-date race, too. Colbert has consistently trailed Fallon in demos since the two began competing in September 2015, continuing a CBS losing streak among younger viewers that stretches back nearly a decade. (David Letterman beat Fallon for one week — his last on CBS — back in 2015, but in terms of extended time frames, the last big Late Show demo win under any host came when Letterman briefly pulled ahead of Jay Leno’s second go-round as Tonight Show host during the 2011 November sweeps.)

In any event, the current demo competition remains fluid. NBC notes Tonight won Thursday and Friday night in the demo, as postelection buzz cooled down a bit. But it’s also possible, maybe even likely, that CBS will pull further ahead once delayed viewing for last week gets tallied. It’s also still very early in the 2018–19 TV season, and Tonight has remained remarkably resilient with younger viewers, even as the show’s overall audience has fallen further and further behind Late Show. (So far this season, Late Show is more than 1.1 million total viewers ahead of Tonight.) Bottom line: Colbert edging Fallon in demos for any length of time is a yuge deal, but it would be foolish to declare this particular skirmish in the late-night conflict settled.