Hot off the wire this morning is that pop's two preeminent bionic women have penciled in Houston for dates on their upcoming tours. First up is Christina Aguilera, who will bring her tiny frame and prodigious voice to the Cynthia Woods Mitchell Pavilion August 12. British diva Leona Lewis, a former winner of the UK's American Idol equivalent, The X Factor, will open.

After paying tribute to influences such as Ella Fitzgerald and the just-passed Lena Horne (R.I.P.) on 2006's retro-swing Back to Basics, Aguilera makes a hard right into Madonna electro/dance territory on Bionic, set to come out next month. Fans who purchase a ticket for Aguilera's show before June 4 will be emailed a link for a free download of Bionic the day before its scheduled June 8 release date.

Tickets begin going on sale Friday, May 21 at livenation.com, although no specific Houston on-sale date has been announced. We'll let you know. Perhaps Aguilera's new robo-bondage look is her attempt to take some of the zeitgeist back from Lady Gaga. Speaking of...

Gaga, who sold out her July 24 and 25 Toyota Center dates in less time than it takes to watch her "Telephone" video, has already begun booking shows for the 2011 leg of her "Monster Ball" tour. She'll be back at Toyota April 8.

Tickets go on sale almost a solid year in advance - this Friday, May 14 at 10 a.m.