For its part, HBO isn't conceding an inch to Showtime. Mark Taffet, the HBO senior vice president who pioneered PPV boxing, told CNBC that the channel will deliver four to six PPV boxing events this year, up from two in 2013.
"We also expect our fights in 2014 to deliver multiples of the 875,000 buys that we delivered in 2013," he said.
HBO gave subscribers newer, up-and-coming fighters in its premium television events in 2013, and its viewership numbers increased "substantially" as the year went on, Taffet said. Perhaps more significantly for a sport that now competes with mixed martial arts, the viewership also began to skew younger demographically over the course of the year.
HBO's younger fighters, such as Ruslan Provodnikov, Mikey Garcia and Sergey Kovalev, are largely knockout artists who draw enthusiastic reviews from both hardcore and newer fans.
"You'll see these fighters in bigger and bigger fights," Taffet said.
—By Senior News Editor Ted Kemp. CNBC's Adam Molon contributed to this report.