Chael Sonnen calls Vinny Magalhaes "the greatest grappler to have ever done it." July 17, Magalhaes will have the chance to prove it, as he faces Ronny Markes in a submission-only showdown.

Submission Underground brings the world's best grapplers under one roof in a submission-only format. Two people enter the cage—one taps out. It's that simple. Watch the inaugural event LIVE on FloCombat.com Sunday, July 17: https://goo.gl/aRJiZ8