Baseball, South Korea's most popular professional sport, will launch its 30th season this weekend, with all eight clubs in the Korea Baseball Organization (KBO) in action across the nation.

The 2011 KBO season starts Saturday with four games starting at 2 p.m. in four cities. The defending champion SK Wyverns will open at home against the Nexen Heroes in Incheon, west of Seoul. The Kia Tigers will host the Samsung Lions in the southern metropolitan city of Gwangju. In Busan, a southern port city, the Lotte Giants will face the Hanwha Eagles.

In the nation's capital, two Seoul-based clubs, the Doosan Bears and the LG Twins, will square off and the Bears will be the home team.

Teams will each play 133 games. SK, Doosan, Lotte and Samsung will play 67 home games and 66 road games this season. The other four -- LG, Hanwha, Kia and Nexen -- will be at home for 66 and on the road for 67.

At the end of the regular season, the top club will advance straight to the Korean Series championship round. The second-seeded team will await the winner of the best-of-five playoff round between the No. 3 and No. 4 clubs.

SK won titles in 2007, 2008 and 2010, while finishing second in 2009. Kia, the 2009 champion, Doosan and Lotte will look to challenge the Wyverns' supremacy this year.

All eight KBO clubs are owned and operated by private corporations, some among the largest conglomerates in the country.

Throughout the season, all weekday games will start at 6:30 p.m. and weekend games will begin at 5 p.m., except for the opening weekend and the Children's Day holiday on May 5, when games will start at 2 p.m.

Baseball has been the biggest draw among the major sports leagues -- football, volleyball and basketball -- in South Korea for years.

The KBO has enjoyed a steady rise in its attendance over the past five seasons, bolstered by South Korea's gold medal at the

2008 Beijing Olympics and a pair of second-place finishes at the 2006 and 2009 World Baseball Classic. Last year, the league set a new single-season record of 5.92 million fans and the eight teams have set out to draw about 6.6 million fans in 2011.

To reach that goal, the teams will need to have an average of 12,462 fans per game, up from 11,144 fans per contest last season.

The league's latest tweak to rules on tie games could keep the pennant race interesting down to the wire.

The KBO in January adopted the third change to the tie rules over the past four seasons. Under the change, ties will no longer count as a loss. In South Korean baseball, ties are called after 12 innings in the regular season and 15 innings in the playoffs.

In 2009 and 2010, the winning percentage was simply calculated with wins divided by the number of games played. This year, the winning percentage will be wins divided by the sum of wins and losses, with ties out of the equation.