DirecTV shares are down about 2% this morning, which is a surprise, because yesterday the company agreed to be bought by AT&T in a blockbuster deal worth $48.5 billion. In early-morning trading, the stock was hovering around the $85 mark, which is about 11% below AT&T’s bid price (which works out to $95 per share).

Why? In a word, American football.

Investors are worried that the deal will collapse if DirecTV is unable to renew its exclusive rights to broadcast every National Football League match on Sundays. DirecTV currently pays an estimated $700 million a season for the “NFL Sunday Ticket” packages. But the existing deal expires at the end of 2014, and AT&T has the right to walk away from the purchase if it isn’t renewed.

On the conference call this morning, DirecTV CEO Mike White tried to reassure investors that the network wouldn’t lose the Sunday Ticket rights.

I am still highly confident that we are going to get our deal done. We have been in active discussions with the NFL. I absolutely expected to be—those discussions to be—consummated before the end of the year, and that will obviously therefore be before the close. So nothing changes from my perspective. Our discussions have been very positive and constructive with the NFL. If anything, I think this unlocks further opportunities for the NFL and for us, and we are very excited about the future together.

AT&T apparently shares that confidence. But all this seems to place the NFL (a non-profit, much to the dismay of some) in a very strong negotiating position, so the new AT&T/DirecTV might end up paying through the teeth for those Sunday games. There has also been speculation that DirecTV could face competition from the likes of Verizon for the lucrative packages.

AT&T stock is also down today, by about 0.4%. Meanwhile, Dish Networks, the seemingly spurned rival satellite operator, has fallen 1.9% on the news that it was passed over. Maybe it will now turn its attention to T-Mobile US? That stock is up 1.5%.