Each of these four players is playing for a first-prize of $750,000. The downside of that -- and it's a big one -- is that they are missing the biggest Sunday Major in the history of online poker. To celebrate five years of the "Sunday Million" tournament on PokerStars, the online poker behemoth guaranteed today's prize pool would be at least $5,000,000. With late registration still open in the tournament, more than 46,000 players already have registered, creating a prize pool of more than $9 million and a first prize that will be significantly bigger than the $750,000 today's NBC Heads-Up winner will receive.