The Zac Brown Band wrapped up their three-night run at Boston's Fenway Park on Sunday (Aug. 9) with an appearance by Aerosmith frontman Steven Tyler, with whom they performed the rock band's classic hits "Walk This Way" and "Sweet Emotion."

Tyler's appearance came near the end of the ZBB's Sunday night set. Press play on the video above to see their rendition of "Walk This Way," and press play on the video below to watch "Sweet Emotion."

Tyler, who is working on his own country album, admits that he is a big fan of the Zac Brown Band, citing their recent single "Homegrown" as one of his favorite country songs.

"Country's the new rock because of people like Zac who aren't afraid to throw in a couple of good guitar licks," Tyler tells USA Today.

In addition to partnering with Dave Grohl of the Foo Fighters for an EP in late 2013, the ZBB also recently sang with the Doobie Brothers on a version of the Doobie Brothers' "Black Water," and their live shows often include songs by Metallica, James Taylor, Pink Floyd and Ryan Adams, among others.

“We take it pretty seriously when we do a cover,” band member Jimmy De Martini says. “We get down note for note and add our own style, too. A lot of the jam bands we grew up with, like Phish and the [Grateful] Dead, they do a lot of covers. We now see, when you’re out there every night, how playing covers can feel new to us, and they’re recognized by the crowd.”

The Zac Brown Band will head to Washington, D.C., Philadelphia and Toronto over the next few weeks. A list of all of their upcoming shows is available on their website.

Watch the Zac Brown Band and Steven Tyler Sing "Sweet Emotion":

See Zac Brown + More Country Stars' Yearbook Photos

Test Your Zac Brown Knowledge