UFC 158: "St. Pierre vs. Diaz" is in the midst of going down tonight (March 16, 2013) at the Bell Centre in Montreal, Quebec, Canada, and the entire mixed martial arts (MMA) community is closely watching.

The event is headlined by a welterweight championship contest as Georges St. Pierre puts his belt on the line for the eighth time against No. 1 contender Nick Diaz, while the undercard on pay-per-view (PPV) will see four more bouts of Johny Hendricks vs. Carlos Condit, Jake Ellenberger vs. Nate Marquardt, Nick Ring vs. Chris Camozzi and Mike Ricci vs. Colin Fletcher.

With anticipation at a high as fans, media and fighters watch the latest Ultimate Fighting Championship (UFC) event go down, we'll bring you live reactions from the Twitterverse during and after the event.

Check out the top Twitter reactions to the UFC 158 main card below.

Remember that MMAmania.com will provide LIVE round-by-round, blow-by-blow coverage of the UFC 158 pay-per-view (PPV) main card action, which is slated to start promptly at 10 p.m. ET. Up-to-the-minute updates and fight-by-fight coverage will begin to flow earlier than that, however, around 6:30 p.m. ET with the "Prelims" bouts on Facebook and FX.

For the latest and greatest UFC 158-related news and notes check out our complete event archive right here.