Jay & Em at Yankee Stadium

EXTRA-BASE HITS: Jay-Z and Eminem’s Yankee Stadium extravaganza Monday night (the first of two dates there) was a star-studded affair, as Dr. Dre and 50 Cent joined Slim Shady— “I want you to feel how much these people love you,” Em said to his mentor—while Hova brought out surprise guests Kanye West, Nicki Minaj and Chris Martin, along with the expected Beyonce cameo. There’s an excellent take in the N.Y. Times by Jon Caramanica, who’s equally insightful about hip-hop and country music. (9/15a)