Christina Aguilera [ tickets ] has cancelled two of four dates she was to perform on the Lilith Fair tour and Tracy Bonham [ tickets ] has pulled out of her entire commitment of two shows. Aguilera is still expected to perform on August 11th and 13th, while her sets on the 10th and 14th will be covered by Bree Sharp, according to Lilith organizers.

Bonham's main stage set on August 1st was covered by Beth Orton, who performed a stretch of July dates on the second stage. Her August 13th set will be covered by Liz Phair.

Aguilera is currently riding the top of the singles chart with her single ''Genie In A Bottle,'' which is setting the stage for her to make a major retail splash with her debut album, due for release on August 24th.

The Lilith Fair tour will wrap up its final North American run on August 31st. Tour co-founder Sarah McLachlan has announced that she intends to retire the tour for the foreseeable future and concentrate on starting a family and on her own recirding and touring career. McLachlan's current release, Mirror Ball is competing with a pair of Lilith Fair live compilations released several weeks prior to Mirror Ball's release.