The Galaxy was, of course, missing loan stars David Beckham and Landon Beckham but also had to play without recently signed goalie Donovan Ricketts, who has been nursing a hamstring injury.
But newcomers Tony Sanneh and Omar Gonzalez put in solid efforts in front of goalie Josh Wicks to earn the shutout for the Galaxy, MLS's worst defensive team in 2008.
A minute before halftime, Buddle scored after a Oita defender failed to control a pass, allowing the Galaxy striker a breakaway attempt, which he put away confidently.
Eight minutes into the second half, Sanneh was held Trinita's Roberto De Figueiredo in the penalty area, and Kirovski put the resulting penalty kick away.
Suwon, the reigning K-League champion, defeated China's Shandong Luneng Taishan FC, 1-0, in the opening game on a late goal by Cho Yong Tae.