Fun. frontman Nate Ruess is set to guest perform with rock legends Queen at this weekend's iHeartRadio Music Festival in Las Vegas.

Both Queen (plus guest frontman Adam Lambert) and fun. are slated to perform tomorrow night, Sept. 20, at the MGM Grand Garden Arena. It is unclear how many songs Ruess will collaborate on, though Billboard notes that the singer was spotted rehearsing "Somebody to Love" and "Fat Bottomed Girls" earlier this week.

The fest, which is set to be broadcast live via Yahoo! Music, features other notable performers such as Muse, Phoenix, Thirty Seconds To Mars, Zedd, and Macy's Rising Star contest winners The Summer Set. Head here for the full lineup.

Fun., who often face stylistic comparisons to Queen, have been known to cover the group's music in the past. Below, check out a few examples.

A cover of "Radio Gaga" from 2010, pre-Some Nights:

Steel Train, fun. guitarist Jack Antonoff's previous band, covering "Under Pressure" in 2010 with Ruess:

And an interview from last year, where the group address Queen comparisons:

Original Queen frontman Freddie Mercury died in 1991. The band have performed intermittently with fill-ins in the decades since. Ruess and fun. are currently winding down their summer "Most Nights" tour with Tegan And Sara.