This happened in Germany on October the 3rd.
Pride FC used a ring but most MMA organisations use a cage in order to avoid entanglements and also fighters falling out of a ring.
Ground and Pound TV shared this crazy video of an MMA fighter sneakily using the ring rope to choke out his opponent:
Sloth Jiu-Jitsu: you can be slow and unathletic and still kick butt in Jiu-Jitsu.