R+B sensation Rihanna has notched up a second week on top of the US singles chart with her international smash hit SOS (RESCUE ME). The teenage singer holds firm at number one on the new Billboard Hot 100 list, keeping Daniel Powter's BAD DAY at number two while Sean Paul's TEMPERATURE rounds out the top three again. Grieving rapper T.I. drops from five to six with WHAT YOU KNOW but he remains atop the Hot R+B/Hip-Hop Songs chart for an impressive fifth week. Chamillionaire's RIDIN' featuring Krayzie Bone is a non-mover at four with Fort Minor's WHERE'D YOU GO, the chart's greatest sales gainer, climbing seven places to five. Nelly Furtado's PROMISCUOUS featuring Timbaland is the chart's highest new entry at number 64.