Just two days before kick-off, the Grammy Award-winning singer-rapper-producer and recent recipient of the NAACP’s Image Award for Outstanding Male Artist brought about a dozen fans on stage for two songs during his nearly two-hour set at the Pepsi-sponsored Super Bowl concert at the massive San Francisco venue. Hand-picking each group from the crowd for back-to-back N.E.R.D hits — guys for “Lapdance” and the ladies for “She Wants To Move” — Williams kept fans, including NFL greats Deion Sanders and 49er legend Jerry Rice, engaged from start to finish. “Hey, San Francisco!” the singer greeted the throng of music lovers as he went into 2014’s clapper, “Come Get It Bae,” wearing a baseball cap, long white coat over a simple T-shirt and jeans ensemble, accented with bubble gum pink Adidas. Childhood friend and N.E.R.D bandmate Shae Haley helped Williams reach back into his cache of hip-hop tunes from the early aughts, and T.I.