It’s been Michael Wacha’s world for the majority of the 2013 postseason. Now he will have to put together another start well beyond his years to save the St. Louis Cardinals’ season and force a Game 7 in the World Series. Wacha will get the ball facing elimination for the second time this postseason as the Cardinals need a victory to hold up a 95-year World Series party in waiting at Fenway Park tonight in Game 6 against the Red Sox. Nothing has seemed to bother the 22-year-old in spots like these despite only having 19 big league starts on his resume, and he’s trying to approach this do-or-die game like he has all of his opportunities since he thrust himself into the national spotlight. “No, I don’t think anything will be much different,” Wacha said via teleconference while the Cardinals were delayed in leaving St. Louis yesterday. “I just try to approach every game the same. I don’t think it’s going to be too much different. We know the next two games are must-wins. It all starts with me.” Wacha has only surrendered three earned runs in 27 innings during the postseason and was particularly strong when the Cardinals’ backs were against the wall in Game 4 of the National League Division Series against the Pittsburgh Pirates. He struck out nine and carried a no-hitter into the eighth inning before Pedro Alvarez gave him his only blemish with a solo home run. Wacha also threw seven shutout innings in the Cards’ pennant-clinching win over the Dodgers. “Michael is very consistent with how he approaches the game,” said Cardinals manager Mike Matheny. “It seems like with every situation that everybody tries to build up around him, the better he pitches. So right now we’re just anticipating him to stay the course. . . . do what he’s doing and hope his stuff will be good enough, and I believe it will with what he’s been doing.” Wacha had success against the top of the Red Sox lineup in Game 2 and will have to do so again with David Ortiz looming and crushing just about everything the Cardinals pitchers hoist to the plate. In his Game 2 win, his lone misstep was Ortiz’ two-run blast in the sixth that snapped a string of 181⁄3 scoreless innings.