Pop queen Britney Spears gushed over country powerhouse Martina McBride during rehearsals for last week's American Music Awards, according to the singer's publicist. Spears told McBride she was a fan, a fact supported by the pop star's friends, who said Spears plays McBride's CDs on her tour bus. McBride's daughter, Delaney, was most excited about the encounter. Spears reportedly knelt down for a tete-a-tete with the 6-year-old. Now back in Nashville, McBride will play the Grand Ole Opry Friday night (Jan. 19).