Word of a collaboration between Dr. Dre and Jay-Z — called “Under Pressure” and to be released as the first single from Detox — cropped up last week, but we considered it baseless, hopeful Internet rumor-mongering. Turns out, it’s really happening! Dre and Jimmy Iovine were at Fenway Park last night for baseball season’s opening day and ran through a promotion for the Beats by Dr. Dre headphones — while wearing Red Sox jerseys and Red Sox–branded versions of the headphones — with NESN’s clumsy pregame reporter. Yes, it was extremely goofy. Also, relevant, because it got Iovine talking about “the new song Dre has in his pocket, called ‘Under Pressure.’ It’s a brand-new single by Dr. Dre and Jay-Z.” Exciting! By the way, the Yankees lost.