SAN FRANCISCO -- On a sunny Tuesday afternoon, with AT&T Park and McCovey Cove as a backdrop, Major League Baseball officials announced the details regarding venues, pools and formats for the 2013 World Baseball Classic.

Tuesday's announcement outlined several changes to the tournament, the third since it began in 2006. Because of the qualification round, the 2013 Classic features 28 countries, an increase over the 16 that competed in 2006 and 2009. The first-round games will feature a round-robin format, with the second round being double elimination.

The U.S. will host games in every round -- Phoenix will be one of four cities hosting first-round games, Miami joins Tokyo in hosting the second round, and San Francisco is hosting the semifinal and final games.

"In a short period of time since it was instituted, [the Classic has] become, really, one of the crown jewels in all of sports," said Larry Baer, the Giants' president and chief executive officer. "It's an opportunity to highlight the global reach of our game and celebrate the cultures and nations that participate in the tournament."

Paul Archey, MLB's senior vice president of international business operations, revealed the four pools of teams for first-round play, which will take place in Phoenix; Fukuoka, Japan; Taichung, Taiwan; and San Juan, Puerto Rico.

The top 12 teams from the 2009 Classic automatically qualified for the 2013 tournament and were assigned to a pool based on "competitive balance, geography and fan interest," Archey said.

The qualifying rounds for the remaining four spots are in progress, with Canada's 11-1 win over Germany and Spain's 9-7 win over Israel sending the two countries to the tournament. The remaining two spots will be determined in November.

Pool A, which will play in Fukuoka, currently features two-time champion Japan, Cuba and China. Taichung will host Pool B, consisting of Korea, Australia and the Netherlands. Pool C, to compete in San Juan, has Venezuela, Puerto Rico and the Dominican Republic. The U.S. will compete in Pool D in Phoenix, along with Mexico and Italy. The fourth country for each pool will be announced in November.

Japan, Korea, Venezuela and the U.S. were in the final four in 2009 and thus awarded the No. 1 seed in their respective pool. The top two teams from the opening rounds will advance to the second round.

The use of the round-robin and double-elimination formats in the first and second rounds, respectively, is a result of learning from what worked well in the past two tournaments, according to Archey.

"Pool play gives us a better opportunity for fans, with broader television coverage, because they know who's playing who, [and also helps in] selling tickets. In the second round, you don't know who's playing, so it doesn't mean as much," he said. "So we can still get that second-round drama, and the first round is really more to draw fans and for greater television exposure."

Additional changes include shortening the schedule by incorporating more doubleheaders -- ensuring that the tournament won't interfere with preparations for the start of the 2013 Major League season -- as well as announcing the 28-man rosters in early December, as opposed to early February as in the past, which gives participating players more time to plan their offseason preparations.

The Giants' Ryan Vogelsong (U.S.) and the D-backs' Miguel Montero (Venezuela) spoke at Tuesday's announcement, with both expressing their desire to compete for their respective country.

"From a players' side, it's part of our responsibility to help promote this game and to inspire the youth of the country to keep playing baseball and to want to be professional baseball players," Vogelsong said. "The [World Baseball Classic] definitely allows us to do that and allows us to have a special experience of putting on the uniform of our country."