Have Pearl Jam really been rocking for 20 years? Actually, it's been 21 -- the band formed in Seattle, Wash., in 1990 -- but that apparent math miscalculation wasn't about to dim the spirits of the thousands of fans who turned up at the Alpine Valley Music Theater in East Troy, Wis., for a two-day birthday celebration and festival being billed as PJ20. Much like Saturday's guest-laden set  check out our recap here), PJ capped off the weekend Sunday with a three-hour, 33-song set that included a healthy mix of all-star onstage collaborations and hits.

Kicking things off with 'Ten' outtake 'Wash' and then quickly tearing through a hits-filled first set that included singles 'The Fixer,' 'Given to Fly,' 'Love Boat Captain,' 'Even Flow' and 'Jeremy,' PJ worked the crowd into a frenzy that could only be topped by what was to come. With a 1st encore that featured a brand new (supposedly written that day) Vedder composition, a cover of a Public Image Ltd. song and a guest appearance by the Frames singer Glen Hansard on ‘Smile,' the intensity only grew.

Then came the biggest thrill of the night. Just like the night before, PJ brought out Soundgarden singer Chris Cornell during their second encore for a reunion of Temple of the Dog, the early-'90s grunge supergroup formed in homage to late Mother Love Bone singer, Andrew Wood. TOTD -- essentially PJ plus Cornell -- played four Temple tunes, including their massive 1991 hit, 'Hunger Strike.' The set closed with Mark Arm and Steve Turner from grunge veterans Mudoney joining PJ onstage for a version of ‘Sonic Reducer,’ a punk classic that Pearl Jam have been covering for years.

Pearl Jam returned for a third encore that included 'Alive,' Neil Young's 'Keep on Rockin’ in the Free World' and 'Yellow Ledbetter,' and with that, they brought to a close the first two decades (plus one year) of one of the most successful rock bands playing today. Don't be surprised if there are two more decades to come. As Vedder told the crowd halfway through his band's set Sunday night, "[Twenty years] doesn't make us feel old. It feels like a rebirth, a new beginning."

Temple of the Dog Perform 'Reach Down' on Night Two of the PJ20 Fest