As introductions to the Red Sox-Yankees rivalry go, Ryan Dempster’s was more of a tease than genuine yesterday. But even with New York bringing in a mostly minor league starting lineup featuring no-names such as Melky Mesa, Zoilo Almonte and Corban Joseph, Dempster offered a reassuring glimpse that he will hold his own when the Hatfields and McCoys square off for real. Dempster was ultra-sharp, holding the Yankees to just one infield single, no walks and two strikeouts in his three innings in the 5-2 Sox loss. Most impressive was that in the mere 28 pitches it took him to record nine outs, 25 were strikes. Dempster quipped the three balls “just missed,” but he was pleased with the quality of his stuff — forget about the fact that Mark Teixeira, Robinson Cano and Derek Jeter were all back in Tampa. “For me, it’s trying to go out there and do your work, I’m trying to focus as hard as I can on the catcher’s glove, making my pitches, regardless of who’s hitting, and you just try to make quality pitches,” Dempster said. “There’s always a play no matter who’s standing inside the box. I felt like I did that today. “Had a good day of pounding the right side of the strike zone, got ahead of most of the hitters and just tried to execute pitches.” Dempster could have kept pitching, but other pitchers needed their work, so he threw about 20 more pitches on a back field after the appearance. Manager John Farrell liked what he saw at JetBlue Park.