The Eagles are shaking up their lineup.

After the legendary rock band took to the stage for their first show at the Las Vegas Sphere earlier this month, fans noticed the group’s guitarist, Steuart Smith, was absent. In his place was singer-songwriter Chris Holt.

Smith, who has toured with the “Hotel California” hitmakers since 2001, is bowing out of the group for now amid a battle with Parkinson’s disease. “It is with profound regret that, due to performance issues associated with my recently diagnosed Parkinsonism, I find that I must bow out of my role with the Eagles while I can still do so gracefully,” Smith said in a statement shared with USA TODAY Monday.

Parkinsonism in Parkinson’s disease refers to an incurable, age-related degenerative brain condition, according to the Cleveland Clinic. As parts of a patient’s brain deteriorate over time, the disease can begin to affect muscle control, balance and movement − particularly important areas for a touring musician.

“It’s been a great quarter of a century, and I had hoped to be able to finish out this year with the band, but I must now do what’s best for all concerned,” the statement continued.

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Holt will serve as the new guitarist, his record company, Idol Records, said in a statement released Friday. In addition to Holt joining the Vegas residency, the statement teased his upcoming album entitled “Across The Milky Way,” expected in early summer.

“Steuart Smith has retired from touring,” Don Henley, a founding member of the rock collective and current drummer and vocalist, added in the statement. “The Eagles will be forever grateful for the extraordinary talents that he brought to both our recordings and live performances. Steuart will be greatly missed, but he will always be part of our musical family. We know our many fans join us in wishing him well.”

In an interview with the Dallas Morning News, Holt acknowledged the important legacy he would be stepping into.

“I’m trying to fill the giant shoes of all three that came before me,” Holt told the outlet. Before him, Eagles guitarists included not just Smith but also Don Felder and Bernie Leadon. “It’s some of the most beautiful guitar work ever recorded, in my opinion. It’s the highest honor for me to do it, and it’s my duty to get it right.”