The San Diego Padres and baseball officials planned to announce Thursday that the semifinals and finals of the World Baseball Classic will be played at Petco Park in March. The World Baseball Classic will be the first international tournament to feature major league players. The Padres have scheduled a news conference for Thursday involving officials from Major League Baseball and the players' association. The San Diego Union-Tribune reported on its Web site Wednesday that the semis and finals will be March 18-20.