Pop rockers Fun pulled out of a concert in New Mexico on Wednesday after frontman Nate Ruess fell sick.

The singer came down with a mystery illness after the band's show in Flagstaff, Arizona on Tuesday and had hoped to recover in time for their gig at Santa Fe's Railyard Park on Wednesday.

However, promoter Jamie Lenfestey was forced to call off the event as Ruess was in no state to take the stage.

He says, "The band showed up here, set up and was ready to go, but Nate didn't feel well. He was almost to the point of being taken to the hospital last night."

The "We Are Young" hitmakers took to Twitter to apologize for the cancellation, writing, "So very sorry to announce we have to cancel tonight's show in Santa Fe due to Nate being sick. Stay tuned for a rescheduled date."