Alicia Keys is still sitting pretty at the top of the U.S. pop charts after claiming a fourth week at number one. The R+B star's No One also scores a ninth week atop the Billboard Hot R+B/Hip-Hop Songs countdown. Timbaland's Apologize jumps up a spot from three to two, while Flo Rida's Low, featuring T-Pain, climbs to three on the new Hot 100. On the Modern Rock chart, the Foo Fighters make history by tying the record for the most weeks at number one. The group's The Pretender claims a 16th week on top - a feat matched only by Green Day, Red Hot Chili Peppers and Staind.