According to setlist.fm, The Boss took the stage with Zach, who was dressed in a Springsteen T-shirt, for his two-song encore, performing the tracks "Sandpaper" and "Revival," with additional help from Bryan's tour opener, Maggie Rogers.
Bryan is set to play a second night at Barclay's Center on Thursday, but his fans shouldn't expect a repeat performance. Springsteen is headed back to the West Coast to play two nights at San Francisco's Chase Center, Thursday and Sunday, March 31. A complete list of dates can be found at brucespringsteen.net.