San Marcos denied Dos Pueblos the opportunity to close out an undisputed Channel League championship on Wednesday by becoming the only team to beat the Chargers twice this season in a 4-2 decision.
A win would have given the league title to Dos Pueblos outright. Now a win for Buena against Ventura on Thursday would allow the Bulldogs a piece of it.
Royals starting pitcher Sean Nakano-West threw four innings. The San Marcos freshman was making one of his few starts this season and allowed just one run.
San Marcos scored all of its runs in the fourth inning, though unearned because of two early errors. Joe Prince then connected for a two-run triple and scored on a single by Jimmy Brakka.
San Marcos finishes its season with a record of 10-17 after finishing league at 4-8.
Dos Pueblos will begin the postseason next week with records of 18-9, 8-4.