It was back in 1997 (I think) in a regular season NHL game. Colorado Avalanche at Detroit Red Wings. The year before in the playoffs, the rivalry was born, when Colorado took Detroit out of the playoffs and Claude Lemiuex had cross-checked Kris Draper into the boards, basically completely damaging his face.
This was the Wings first chance at revenge, and the question wasn't whether it was going to happen, but when it was going to happen. Sometime around the 2nd period, right after a faceoff at center ice, Darren McCarty jumped Lemiuex and just began pummelling him with his fist. Lemiuex was in the fetal position on the ice, creating a bloody mess near the boards. As this was going on, the other 8 skaters were squaring off.
Just when I didn't think it could get any better, it did. I saw Patrick Roy out of the corner of my eyes skating toward the melee. Brendan Shanahan, while tangled with someone else, saw him coming and basically closelined him. That's when our goalie, Mike Vernon got involved, and him and Roy went toe to toe for what seemed like an eternity.
Later in the game, we were trailing 5-4 (I think Kamenski had a hat trick) and we tied it. In OT McCarty knocked home the winner. This win single handedly gave the Wings the confidence to knock them out in the playoffs, and go on to 2 straight titles.
The next best part about it was that I had money on Detroit -0.5, and also had money on OVER 7 (remember O/U's of 7 or 8 in hockey?).
That was my favorite sporting event. I'm sure 100,000 people in Detroit claim to have attended that one.