Pearl Jam's weekend-long 20th birthday bash in Wisconsin was packed full of surprises, the biggest of which had Chris Cornell joining the band for Temple of the Dog classics like 'Hunger Strike' and 'Say Hello to Heaven'.

Pearl Jam and Soundgarden fans have coveted a Temple of the Dog tour for a very long time. Those who were lucky enough to attend PJ20 over the weekend  got exactly that. Eddie Vedder passed the stage to Cornell for a few songs each night and provided the members a rare opportunity to play some songs together that they haven't in 20 years.

Temple of the Dog was a collaboration project featuring Pearl Jam's Mike McCready, Stone Gossard, Jeff Ament and Soundgarden's Chris Cornell and Matt Cameron (who ironically later became Pearl Jam's drummer and still holds that gig). The group formed as a tribute to Andy Wood, the singer of Jeff and Stone's previous band Mother Love Bone, who died of a heroin overdose.

The quintet released a self-titled album in 1991 which spawned the hit single 'Hunger Strike' featuring the then unknown Eddie Vedder -- who was the singer of Jeff and Stone's new project, Pearl Jam. The band only played a single one hour set immediately following the album's release and have rarely shared a stage together since.

The PJ20 Festival at Alpine Valley Music Theatre served as the second and third longest performances from the band, who played four songs each night. The first night Cornell took over as vocalist of Pearl Jam and opened with the Mother Love Bone track 'Stardog Champion' as well as the TOTD songs 'Say Hello 2 Heaven', 'Reach Down', and 'Hunger Strike' (which Vedder re-joined them for).

The second night's Cornell cameo opened with 'Hunger Strike', then Vedder left the stage while the band played 'Call Me a Dog' -- which Chris announced they hadn't played together in 20 years. They finished their set with 'All Night Thing' and 'Reach Down'. Chris said he forgot some lyrics the previous night and wanted another shot at the closer -- it ended up being one of the festival's best performances the second time through.

Temple of the dog - night 1

Temple of the Dog - Night 2