The 2012 Major League Baseball season began on March 28 with the first of a two-game series between the Seattle Mariners and the Oakland Athletics at the Tokyo Dome in Japan. On November 22, 2011, a new contract between Major League Baseball and its players union was ratified, and as a result, an expanded playoff format adding two clubs will be adopted no later than 2013 according to the new Collective Bargaining Agreement. The new format was finalized for the 2012 season on March 2, 2012, and will use the 2–3 game schedule format for the Division Series for the 2012 season only. The restriction against divisional rivals playing against each other in the Division Series round that had existed in previous years was eliminated, as the Baltimore Orioles and New York Yankees squared off in one of the best-of-5 LDS series in the American League. The stateside portion of the regular season started April 4 in Miami with the opening of the new Marlins Park, as the newly renamed Miami Marlins hosted the defending World Series champion St. Louis Cardinals. The regular season ended on Wednesday, October 3. The entire master schedule was released on September 14, 2011.