Reese Witherspoon has two words for Katy Perry and Taylor Swift: "I'm sorry."The actress told E! at the Toronto International Film Festival that she's personally apologizing to both pop stars for her upcoming animated movie Sing, where she plays a pig with 25 kids who enters a singing competition looking for a fresh new start.In the film, out December 21, Witherspoon does her own renditions of Swift's "Shake It Off" and also Perry's "Firework," but she doesn't feel it really does the two women justice. Hence, all the apologizing."I saw them and said, 'Please don't hold it against me because I did the best I could,'" Witherspoon said. "I was like, 'I have really a lot of respect for how hard you girls work.'"Of course, it's hard to believe Witherspoon's latest singing performance isn't award-worthy being that she won an Oscar for her portrayal of country legend June Carter Cash in Walk The Line.Witherspoon did her own singing in that one so it's hard to believe she'll have anything to be truly sorry about with Sing.Now, if Witherspoon could get Swift to apologize to Perry then that would really be something.