The Dave Grohl Roladex is getting a workout these days. Earlier we showed you the Foo Fighters singer inviting his doctor, Lew Schon, onstage at Boston's Fenway Park Sunday night for a performance of White Stripes' "Seven Nation Army." But Schon wasn't the night's only special guest. Godsmack's Sully Erna was up for a little Beantown bro-down with the Foo Fighters as well.

As seen in the fan-shot video above, Erna took lead vocals while Foo Fighters provided a pretty awesome backing band on a cover of the Alice Cooper classic "School's Out." Sporting his trademark bandana and wearing a "Boston Strong" t-shirt, Erna delivered an energized performance of the Cooper track for his hometown fans.

As he ended the song, Erna stated, "What an honor to be on the stage with what I feel is probably the greatest f---ing American band on this planet right now." After making the proclamation, there were handshakes all around as the band finished out the song.

Foo Fighters are heading off to Japan and South Korea for a few shows, but will resume their North American tour Aug. 12 in Edmonton, Alberta. Their dates can be found here.

As for Erna, he'll be back with Godsmack on tour at the beginning of August. Their trek resumes Aug. 1 in El Paso, Texas with dates booked into late October. See their upcoming shows here.

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