Sky considers BT to be a genuine rival in the UK subscription TV market, it has been claimed.
Sky Sports' Managing Director Barney Francis told the Leaders in Football conference that his firm is aware of the threat posed by the telecoms giant, reports Reuters.
BT recently secured the live rights to top flight rugby and 38 Premier League football matches a season from 2013-14 - including some of the top-pick matches.
Although BT Vision currently only has around 700,000 customers - compared to Sky's ten million - the acquisition of live football and rugby could encourage more households to sign up.
And this is why Mr Francis says Sky is taking BT "very seriously".
"We know the nature of the Premier League process means there has to be a competitor and competition like that keeps us on our toes," he added.
Sky has been the main broadcaster of Premier League football since the 1992-93 season.