Zac Brown Band played two sold-out shows at Fenway Park over the weekend, and Friday's show (June 27) included a very special musical guest: the Doobie Brothers.

It was a captivating evening already, as Brown confessed that Fenway Park might be “my favorite place that I’ve ever played.” And when the Doobie Brothers joined the country group onstage for a rousing rendition of 'Black Water,' it may have been country fans' favorite version of the song that ZBB has ever played.

It makes sense the the rockers would join ZBB onstage. In February, they announced country stars, including the 'Chicken Fried' hitmakers, would help them record an album of their hits.

The two-and-a-half hour show, complete with songs like David Allan Coe’s 'You Never Even Called Me by My Name' and the Outlaws’ 'Freeborn Man' turned into a three-hour show, much to the delight of attendees.

Early on, Brown declared that the band would be their own opening act, and promised fans they would play for three whole hours. The encore (which happened after they closed out with 'Chicken Fried') included ZBB dressed in glow-in-the-dark skeleton costumes and a cover of Pink Floyd's 'Comfortably Numb,' as well as 'Devil Went Down to Georgia.'

It was an all-around country-filled weekend at Fenway Park. In addition to ZBB's sold-out shows and the Doobie Brothers' appearance, the country group surprised Billy Joel concertgoers on Thursday (June 26), performing 'You May Be Right' with the piano-playing star.

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