(Adds comment from analysts, advertisers)
By Sheila Dang
Sept 8 (Reuters) - The NFL kickoff game broadcast on Thursday night on NBC, a win by the Kansas City Chiefs over the New England Patriots, attracted 21.8 million TV viewers, down more than 13 percent from last year's opening game, data from NBC and Nielsen showed.
Last year's game between the Carolina Panthers and Denver Broncos, also on Comcast Corp unit NBC, drew 25.2 million TV viewers.
Despite competition for attention, advertisers and television networks are optimistic for this season due to a more compelling game lineup and the NFL's traditional broad reach.
Viewership of the Thursday night game was probably reduced as fans in Texas, Florida and Georgia focused on recovering from Hurricane Harvey and bracing for Hurricane Irma, said Jason Kanefsky, director of strategic investments at marketing firm Havas Media Group, in an interview.
Still, this season's NFL primetime lineup of match-ups between highly ranked teams is improved from last year, said Michael Nathanson, senior research analyst at MoffettNathanson, in a note on Wednesday.
The schedule could stoke enough excitement among fans to bring up to 5 percent viewership growth for NBC's Sunday Night Football, Nathanson said. Walt Disney Co's ESPN, which holds the rights to Monday Night Football, could see 11 percent growth over last year.
Except for the Olympics, nothing compares to the NFL in the eyes of advertisers, who remain optimistic this season, Kanefsky said.
"The ratings may be coming down, but it's still an unbelievable media vehicle," Kanefsky said of the NFL. Havas' brand clients planning to buy ad time this season include those in retail, pharmaceuticals and banking, Kanefsky added.
NFL interest is still largely driven by Baby Boomers and Gen X viewers, large attractive audiences for brands, said Michelle Palmer, president The Marketing Arm, a sports marketing agency whose clients include insurance, communications and auto companies.
The 2016 presidential election campaign hurt ratings last season, analysts have said. Viewership rebounded after the November election, but was still down 5 percent from the previous season. Amy Yong, an analyst at Macquarie Bank who covers Comcast, said advertising rates for games aired on NBC are expected to hold steady or even increase despite lower ratings, due to the network selling fewer ad spots and using digital to help their ad reach. (Reporting by Sheila Dang in New York; Editing by Leslie Adler and David Gregorio)