US Open Odds: Origins of the US Open Odds Game at SBG Global. Not many people are aware, but the US Open odds game is the oldest professional tennis tournament in the world. US Open betting has been around for more than a century and the US Open odds game has been delighting fans from around the world since 1881. With that kind of longevity is no wonder that the US Open odds game remains one of the fan favorites and one of the best Grand Slam events on tour.