Black Sabbath have unveiled another new track live during the overseas road trek to promote their upcoming album '13.' At a concert in Melbourne, Australia on Monday (April 29), the group performed 'Methademic,' which is slated for release as one of three bonus tracks on the deluxe edition of '13.'

From the limited sound of the audience-shot footage above, the song sounds like it centers around a classic heavy Sabbath riff. It's also got a strong melody, as far as anyone can tell -- though it must be said, even allowing for the dodgy recording quality, it seems that this performance is far from Ozzy Osbourne's best moment vocally.

Past Sabbath reunions have been dogged by the singer's increasingly limited vocal range, and this clip doesn't exactly soothe fan fears that he might not be up to a full tour vocally. It starts off spotty enough even in his lower range and progresses to almost tuneless caterwauling by the end of the song, with Ozzy barely pronouncing the words enough to distinguish any of the lyrics.

Tony Iommi saves the track with a typically compact, awesome solo. Fans can only hope that this was an off night, and that the studio version of the track will contain a much stronger vocal performance.

This marks the third track we've heard so far from '13' -- Sabbath have released one single, 'God is Dead?,' and they premiered another track, 'End of the Beginning,' on the opening night of their tour.

'13' is set to drop in several formats on June 11. Black Sabbath will kick off a North American summer tour on July 25 in Houston, Texas.