Anyone doubting the sales potential of a game with the words "Wii Sports" in the title need only look at some figures from Europe, which reveal the game is selling even more there than it is in the US.
Last we saw, Wii Sports Resort has sold 500,000 copies in the US since launch. And that was earlier this week. In roughly same timeframe, it's sold 600,000 copies in Europe. Add that to the 350,000+ sales its racked up in Japan, and yes, we're looking at our first serious challenger for "biggest-selling game of the year".