UFC 199 was due to be Luke Rockhold rematching Chris Weidman for the middleweight title, but Weidman's neck injury sprung Michael Bisping into action, keeping the rematch element of the Saturday, June 4th main event alive.
These two have generated quite the hatred for each other, certainly more attention-grabbing than Rockhold and Weidman did in their first fight. Less than two years ago, Rockhold dropped and choked out Bisping in a UFC main event in Australia, making him the first and only fighter to submit "The Count." Now he'll have to make his first title defense against Bisping, but with the Brit coming in on short notice.
As you can imagine, there was an intense staredown between the champion and the challenger. Plenty of words were exchanged, even after Dana White intervened. You can watch the video at the top of the page, courtesy of MMA Fighting. Note the gesture Rockhold makes at the :23 mark.