Cream and Buffalo Springfield both got off to fast starts in 1966 -- and both bands fell apart two years later. Now their paths cross again as they're forced to face off in the newest round of the 100 percent fan-voted Ultimate Classic Rock Hall of Fame.

Commonly referred to as rock's first supergroup, Cream got their start after drummer Ginger Baker came to watch Eric Clapton perform in his role as guitarist for John Mayall and the Bluesbreakers. Bonding during a car ride after the gig, Clapton agreed when Baker asked him to join a band he was thinking of starting -- on the condition that they hire Jack Bruce, a former bandmate of Baker's in the Graham Bond Organisation, to sing and play bass.

The trio's talent was undeniable -- they drew their name from popular perception that they were the cream of the British blues crop -- but Baker and Bruce hadn't gotten along during their tenure with Bond, and their relationship remained strained even as they thrilled concert crowds and shattered sales records with their heavy blend of blues, jazz and psychedelic rock. By the end of 1968, it was over; their fourth and final album as a band, a live/studio hodgepodge titled 'Goodbye,' arrived in the spring of 1969.

While Cream were getting started in the U.K., Buffalo Springfield were coming together in Los Angeles, the result of a broken record deal suffered by Canadian Motown act the Mynah Birds after their singer, future legend Rick James, was arrested for going AWOL on the Navy. At loose ends, bassist Bruce Palmer and guitarist Neil Young headed to California, where they planned to meet up with Stephen Stills, a session musician and acquaintance of Young's.

James' arrest ended up becoming folk-rock's gain after Palmer and Young met up with Stills; along with drummer Dewey Martin and guitarist, singer and future Poco founder Richie Furay, they formed Buffalo Springfield, and had their first LP in stores by the end of '66. But as with Cream, personality conflicts proved a major problem, and by the time they got around to finishing up tracking for 1968's 'Last Time Around,' it was all but over.

While neither band was meant to last, they both remain pivotal points in their members' careers, and residual affection for those classic records has helped inspire periodic reunion shows for each of them. So who will move on to the semifinals? That’s entirely up to you. You can vote once an hour between now and Dec. 15 at 11:59PM ET. This month’s winner will be announced on Dec. 29. Be sure to read our official rules.