Brussel fans were left disappointed as Queen + Adam Lambert concert was cancelled. The "American Idol" alum took to Twitter to appease those who already bought tickets to the show.

Adam Lambert couldn't go through with the concert with Queen because of severe bronchitis.

"The group played their last concert in Frankfurt, Germany," said Unreality TV. "But the effort left Adam feeling more than just under the weather and a press release today has revealed that the singer sought medical attention after the show."

Adam Lambert tweeted: "Brussels: sad we had to cancel tonight. The last thing I'd want is to let u down but I'm under doctors orders to stay in bed and get well."

He added: "Thanks for the well wishes guys! Send me some healing energy, I'll drink a ton of water and sleep! Sound like a plan?"

Organizers released a press statement that said: "Queen and Adam Lambert have this afternoon reluctantly been forced to announce the cancellation of their sold out Brussels concert scheduled to take place tonight, Sunday February 8 at Palais 12, Brussels."

Fans who bought tickets to the Queen + Adam Lambert tour will be refunded, but they will have to travel to Mediolanum Forum in Milan if they want to watch the legendary band rock with the "American Idol" alum.

The rest of the tour will go on as schedule.

Adam Lambert and Queen first collaborated in 2009 to perform "We are the Champions" at the "American Idol" season 8 finale. In 2011, they teamed up once again in Belfast during the MTV European Music Awards.

Legendary guitarist Brian May told Irish Times that they are fortunate to have stumbled upon Adam Lambert for the Queen tour.

"It's not Freddie, you know," he said. "He doesn't for an instant try and be Freddie. But some of the stuff he brings is very, very parallel, very similar, you know, the likeness he brings, apart from the extraordinary instrument, I mean, incredible instrument he has as a vocalist."