Sources close to TLC [ tickets ]'s "Fan Mail" tour confirm that Christina Aguilera [ tickets ] will join the tour in January as an opening act, and that Destiny's Child [ tickets ] will retain their support slot. TLC has recently added 14 cities to the second leg of its North American tour, having skipped many major markets during the first leg.

Aguilera, the former Mouseketeer who topped the pop charts earlier this year with the single ''Genie In A Bottle,'' told MTV in September that she would be joining the TLC tour in November, but wound up on the sidelines for its initial leg.

The ''Fan Mail'' tour opened last month with a series of Canadian shows. Its first leg will conclude Nov. 24 with a performance at Conseco Fieldhouse in Indianapolis. After breaking for the holiday season, the tour's second leg will open on Jan. 3 at the San Diego Sports Arena.

The jaunt will wrap up with a Jan. 24 stop at Philips Arena in TLC's hometown of Atlanta, according to TLC's official website.

In related news, a webcast featuring a live performance of three No. 1 TLC singles--''No Scrubs,'' ''Unpretty'' and ''Waterfalls''--is available online at the MP3.com website. The live appearance, which was TLC's first since 1995, was recorded in Tokyo last summer. It will be available free online through Dec. 5.