According to UK newspaper the Guardian, it is believed BSkyB makes around £2.50 a month on each subscriber who takes up ESPN's new channel, which launched last month and is showing 46 live Premier League matches this season.
ESPN picked up the live rights to English football's top-tier division following the collapse of the UK-arm of pay-broadcaster Setanta.
Analysts at Citigroup calculate that BSkyB will make as much as £80 million a year providing it targets 2 million subscribers.
"Sky has been a bit more generous to ESPN [than Setanta] in its choice of potential games this season in order to help ESPN's channel business," said a Citigroup note.
"The downside, of course, is that if ESPN is really successful it may feel emboldened to extend its content acquisition strategy. Which in time at best would lead to greater sports rights inflation and at worst could pose a material challenge to Sky's dominant position as an aggregator of premium sports content in the UK."
The Disney-owned broadcaster has struck distribution deals for its new UK channel, which launched at the start of August, with several UK platforms including Sky, Virgin Media, Freeview and BT Vision.
