As the broadcast networks’ new-look late-night lineups battle for eyeballs on the traditional medium of linear television, a separate and increasingly important battle is being waged for digital buzz. And in the digital arena, the gap between NBC’s segment-leading Jimmy Fallon and CBS’s upstart Stephen Colbert is even wider than it is in linear TV, the New York Post reports.

The report cites ListenFirst Media, which measures tweets, hashtags, likes and wiki searches to come up with a figure representing digital “engagement.” ListenFirst data shows Fallon with a whopping 715.5 million “engagements” in the fourth quarter, dwarfing Colbert’s 121.9 million. In fact, Colbert is so far behind on the digital front, according to the report, he fails to make the top five among late-night shows, and even trails his CBS lead-out, James Corden.

Corden comes in at No. 4 with 176.6 million engagements. But the report notes that the rest of the field has a significant head-start on Colbert, who has only been in the game for four months.

“The 51-year-old funnyman, who replaced David Letterman as the host of CBS’s ‘The Late Show’ in September, is struggling to deliver the viral videos and other comedic bits that have propelled YouTube leader Jimmy Fallon to the front of the late-night pack,” the Post reports.

“What’s more, Colbert’s YouTube channel has racked up just 684,000 subscribers since viewers got their first glimpse, while Fallon has a whopping 9.3 million,” the report adds.