They both made it through the first round, and now Stevie Ray Vaughan and Dio will have to battle each other for a spot in the Ultimate Classic Rock Hall of Fame.

Both acts earned decisive victories in Round One, with Vaughan earning more than 56 percent of the reader vote against Metallica and Dio racking up a whopping 88 percent landslide over Don Henley. But now that the Bay Area metal legends and Mojo Nixon's arch-nemesis have fallen in defeat, the semifinal round promises an even tougher fight -- and UCR readers will have to decide who wins.

Although they occupied different spots on the rock 'n' roll spectrum, Vaughan and Dio both enjoyed breakout success in the '80s -- Vaughan as a highly respected guitarist on the Austin scene who made a name for himself as an incredible live performer before breaking the Top 40 with his debut solo LP, 1983's 'Texas Flood,' and Dio as the namesake and new band fronted by former Black Sabbath vocalist Ronnie James Dio after he left the group in 1982.

Dio's debut, 'Holy Diver,' also arrived in 1983, and both acts matched each other album-for-album every year until 1985, with Vaughan releasing subsequent Top 40 successes 'Couldn't Stand the Weather' (1984) and 'Soul to Soul' (1985) before beginning a four-year studio hiatus that included 1986's 'Live Alive' concert album. Dio, meanwhile, continued to enjoy worldwide success with 1984's 'The Last in Line' and 1985's 'Sacred Heart' before ending its bestselling run with 1987's 'Dream Evil.'

Vaughan was sadly unable to build the lengthy discography that earlier efforts promised, battling back from sobriety struggles to release the critically acclaimed 'In Step' in 1989 and collaborating on 'Family Style,' a duo project with his brother Jimmie, before tragically passing away in a helicopter crash on Aug. 27, 1990. Dio continued to release albums into the 21st century before calling it quits with 2004's 'Master of the Moon,' and although subsequent efforts didn't sell as well as those early releases, Dio enjoyed a late-career resurgence when he rejoined his former Sabbath mates to create the new band Heaven & Hell in 2006. Heaven & Hell came together in the studio for one album, 2009's bestselling 'The Devil You Know,' but their run was cut short by Dio's own untimely death from stomach cancer in May 2010.

So who moves onto the finals? You can vote once a day between now and Monday, Oct. 27, at 11:59PM ET. The winner will be revealed on Nov. 4. Be sure to read our official rules.