Carrie Underwood will join Brad Paisley on the final leg of his Time Well Wasted 2006 tour that kicks off Sept. 22 in Birmingham, Ala. The tour will hit 25 other cities, including Atlanta, Cincinnati, Baltimore, Houston, Oklahoma City, Salt Lake City and Las Vegas, before closing Dec. 8 in Chicago. In its attendance tally for country tours during the first six months of 2006, Paisley was in fifth place, behind Tim McGraw/Faith Hill, Kenny Chesney, Rascal Flatts and George Strait. "The World," the latest single from Paisley's Time Well Wasted, album is spending its third consecutive week at No. 1 on Billboard's country singles chart.