Def Leppard [ tickets ], which recently had to cancel four Canadian shows due to illness, was forced to cancel two more shows while lead vocalist Joe Elliott recuperates from an upper respiratory tract infection, according to a statement on the band's website.

The tour was expected to resume in Grand Rapids, MI, today (4/18), however Elliott's recovery did not go as well as was hoped. In addition to the April 18 Grand Rapids concert, the April 19 show in Detroit has been postponed until further notice. Information regarding rescheduled dates will be posted on the band's site as the information becomes available.