By Stephen M. Silverman
Updated March 22, 2004 01:40 PM

Britney Spears’s fans in the Midwest were disappointed this weekend after a knee injury forced the pop princess to cancel some playdates.

The “Oops!” singer, 22, hurt herself — and thereby stopped the show — during a dance number near the end of Thursday’s Moline, Ill., performance, while she was singing one of her new songs, “Boom Boom,” reported TV’s “Entertainment Tonight.” She then re-emerged onstage in a white bathrobe and reportedly apologized to the audience for not being able to deliver her two encore numbers.

A new date for that show, sometime in April, is expected to be announced this week, says Reuters.

Spears also postponed a performance Friday at the Allstate Arena in the Chicago suburb of Rosemont, Ill., where some 15,000 fans were expected. (They’ve been told to hold on to their tickets until further notice.) Sunday’s Flint Journal in Michigan reported that the evening’s concert at the Palace of Auburn Hills was also canceled.

Spears’s Onyx Hotel tour, which kicked off March 2, will run through the summer.

The tour is expected to resume Tuesday in Atlanta, according to a statement from Spears’s label, Jive Records. This should help keep the road smooth for her March 28 concert in Miami, which is slated to be broadcast live on Showtime.

Already it is being advertised with the slogan “All Britney, All Live.”