3rd Referee NCAA men's Tourney
 

Watching the NCAA Final 4, I noticed a third referee sitting behind the "up" official during both semifinal matches...Anyone know the reason for this?

The R3
 

The R3, from what I've been told, handles substitutions, facilitates TV timeouts, and does a little "serving and protecting" of the R1 if needed. The first two are the primary responsibilities.

Another forum indicated that part of this was because to cut down on the number of cameras needed to cover the match, they put the teams on the R1 side, so the R3 handles subs from the R1 side of the court.

This is easy - they are there in case topside official gets excited and falls off tower, injures themselves and cannot continue. :D

Having fallen off a wooden stand that was poorly built and fell apart at a hole in the ground school, I can certainly understand the reasoning!