On Sunday, millions of real-time TV viewers will be faced with a difficult decision: whether to watch the season finale of AMC's "The Walking Dead" or the season premiere of HBO's "Game of Thrones."
Their choice could impact Nielsen ratings and bragging rights for each show. Both highly anticipated programs air Sunday at 9 p.m. ET.
"The Walking Dead," a horror-drama set in the months after a zombie apocalypse, has become a financial boon for AMC, boosting television ratings and lifting advertising revenues to become one of the network's most valuable shows. "Game of Thrones," a fantasy series modeled after George R.R. Martin's best-selling epic novel series "A Song of Ice and Fire," is similarly valuable to HBO and parent company Time Warner, helping the network expand domestic subscriptions and revenue in 2012.
In the Nielsens, "Walking Dead" has been a clear winner, placing first in cable on Sunday night for the most recent episode, with a 5.4 rating in the core 18-49 demographic and 10.99 million viewers total, according to TVByTheNumbers.
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Its ratings have been so strong (ranging between 9.21 million to 12.26 million viewers this season) that the network runs a complementary show "Talking Dead" after each episode to recap the action. This week, "Talking Dead" drew 4.4 million viewers with a 2.2 rating in the core demographic.
In contrast, last season's finale of "Game of Thrones" had a 2.2 rating with 4.2 million total viewers and was the highest rated episode of the season.
Unlike AMC, which uses advertisements as a key source of revenue, HBO does not show commercials and instead charges a monthly fee for access. So HBO is less concerned about what viewers decide Sunday, it just wants people to watch—whenever they can.
"On average over 80 percent of viewership for an HBO series occurs after the initial airing," HBO spokesman Jeff Cusson said via email to CNBC.com. "Our subscribers utilize every platform, as well as watching replays throughout the week, so we focus on gross audience."
On top of this, several cable operators are expected to provide free HBO service to all subscribers this weekend, increasing the potential audience.
For AMC, the ratings, which are used to set advertising rates, are not likely to be significantly affected. JPMorgan media analyst Alexia Quadrani said that financially speaking, the scheduling overlap should be a "moot point" for both networks, since the standardized currency for pricing TV advertisements, the Nielsen C3 metric, includes time-lagged viewership up to three days later.
"Any viewership that is lost will probably be picked up in the three-day window. If you're going to catch 'The Walking Dead' finale the next day, it's going to be just as good for AMC," she said. "There is overlap and for the likely viewer that is attracted to both of these shows, that person will be watching both."
Still, AMC CEO Joshua Sapan noted in the Q4 2012 conference call that "The Walking Dead" drove records for basic cable TV, and CFO Sean Sullivan said increases in advertising revenues were due to original scripted programming, "most notably" the zombie series. In the quarter, AMC reported advertising revenues of $157 million, a year-over-year increase of 16 percent.
When asked about the scheduling faceoff, an AMC representative welcomed the challenge, telling CNBC.com: "It makes for a great night of television."
Quadrani, who covers AMC Networks and Time Warner, told CNBC.com that "there is no question that—on both sides—you're going to see a little shaved off the top (in the ratings). If they weren't competing for that time slot, ratings would be higher for both shows."
Although the price of advertising numbers for individual shows are not made public, a highly anticipated episode like the season finale of "The Walking Dead" may cost advertisers more than $375,000 for a 30 second spot, potentially as much as $500,000, said Quadrani, referring to comparable numbers calculated by AdAge.
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This season, two of the major sponsors of "The Walking Dead" are Hyundai and AT&T, which are referenced before commercial breaks. Hyundai is also notable for its product placement in the show, as the characters have driven a Hyundai Tucson through the post-apocalyptic world for several seasons.
When asked about the scheduling tete-a-tete, Hyundai told CNBC.com that "The Walking Dead" "continues to offer Hyundai a terrific platform. We're confident that 'Walking Dead' can more than hold its own against any competition."
AT&T did not respond with a comment.
Numerous large companies have placed advertisements with AMC during "The Walking Dead," including Apple, JC Penney, Microsoft, DirecTV and Expedia.
Despite the scheduling conflict, for the most part fans don't seem to mind and are taking to Twitter to show their excitement. A tweet by a fan of both shows, Brett Callan, perhaps summed it up best: "This coming Sunday: The Walking Dead season 3 finale. Game of Thrones season 3 premiere. EASTER. how can you be bummed? #winning"
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— By CNBC's Paul Toscano. Follow him on Twitter @ToscanoPaul
Analyst Disclaimer: AMC Networks has been a client of Alexia Quadrani's firm, JP Morgan, within the past 12 months.