To get this far in the NCAA tournament, the 16 teams still alive needed a good mix of clutch performance, mistake avoidance and luck. They also all had to have something they could rely on above all else to get through the first weekend and be part of a select group of schools that are only two games from the Final Four.
It could be a player, a facet of the offense or defense, or possibly a statistical area in which each team excels. Whatever the case, this thing is as responsible for a school's success to this point as anything else. It also has to continue going the team's way for it to advance further.
We've identified the X-factor for each Sweet 16 participant, explaining its role in getting the team this far and how it will impact the next game and possibly beyond.