Dave Grohl invited his orthopedic surgeon, Dr. Lew C. Schon of Baltimore’s MedStar Union Memorial Hospital, to share the stage with him during the Foo Fighter’s concert at Fenway Park in Boston on  July 19.

Dave Grohl Performs With His Orthopedic Surgeon

Together, Grhol and Schon covered The White Stripes’ “Seven Nation Army,” Grohl sitting in his enormous and psychedelic throne, and Schon singing the lead vocals.

Schon took care of Grohl’s leg when it broke on stage in Sweden last month. According to MTV, Schon didn’t come to Boston only to perform. He was originally invited to check up on Grohl’s injury. Then Grohl asked him to perform, and Schon proved he’s the coolest doc ever by saying yes.

Schon told MTV News that Grohl knew he was a musician before inviting him to perform. “My band’s called The Simulators. I’m known more for maybe my stage personality and maybe through piano-playing spirit. I usually sing backup harmonies and I usually do character songs.”

The doctor also said he was comfortable being in front of thousands of people. “I used to do magic,” he said, “and I juggled and I give lots of lectures, so I’m very comfortable performing because I have a band.”

Slightly different from the rock anthem “Seven Nation Army,” but after only one rehearsal, he was ready to rock Fenway Park. “I wasn’t so intimated by being in front of 40,000 people or whatever the number was, but I definitely wanted to make sure that the people were going to be happy,” he added.

After their performance, Grohl exclaimed, “Holy sh-t, that’s actually my doctor!” adding “What a badass.”

The audience loved the performance, confirming a recent promise Grohl made to Entertainment Weekly. “The shows we’ve been doing lately are some of our favorite shows we’ve ever done, and I’m not f—ing kidding. This throne and these crutches and these audiences make us play longer and harder than we ever have,” the Foo Fighters frontman told the magazine.

The Foo Fighters will be back in the U.S. on Aug. 14 for a show in Walla Walla, Wash., before heading to Colorado, Missouri, Minnesota, Michigan, Pennsylvania, Indiana and Illinois.

You can find information on Foo Fighters tickets here.