The Illinois State Fair on Monday announced it has added a free concert to its Grandstand lineup. It'll be another two weeks before we know for sure who is performing, however.

The concert will happen on Thursday, Aug. 8, after the Twilight Parade, a night when the Grandstand is normally dark.

Fair officials did not reveal the name of the performer(s) — other than to say it is a "big-name act that everyone will recognize" — and instead set up a contest for people to guess the artist in an effort to win backstage passes to meet the performer.

Clues about the artist will be posted daily starting Monday through July 5 on the Illinois State Fair's Facebook page. To make a guess, entrants must send a Facebook direct message to the fair by July 7 at 11:59 p.m.

The name of the act will be announced on July 8 on Midwest Family Broadcasting radio stations.

People who correctly guess the artist will be put into a drawing, and 10 entrants will receive the backstage passes, along with free admission and parking to the fair on that night. Winners must be 16 or older and be able to show a valid photo ID.

The state fair is still working to fill one hole in the Grandstand lineup. Legendary heavy metal band Megadeth last week canceled its Aug. 9 show at the fair due to the illness of its lead singer. The fair said last week it was trying to find a replacement act for the evening.