Blackburn will play Vilnius Vetra in the third round of the Intertoto Cup after Uefa threw Legia Warsaw out of this year's competition.
Vetra led Warsaw 2-0 in their first leg second round match in Vilnius on Sunday, but the match was abandoned when Polish fans began rioting.
Uefa's disciplinary body has also banned Legia Warsaw from European competition for the 2008-09 season.
Blackburn will travel to Vilnius for the first leg on 22 July.
The return leg takes place the following week.
Legia have also been ordered to contact Vetra within ten days about compensation.
Uefa's disciplinary body added: "Legia must react quickly and firmly if the club wishes to participate in Uefa competition in future.
"With Legia's considerable disciplinary record for away matches, the duty of playing matches against Legia becomes a tall order that Uefa cannot afford to support any longer."