But it isn't straight 1v8 (etc).
Bracketing principle is to balance the four regions for 1-4 seeds as closely as possible (I think target is within 5 ranking points).
So you could get any of 1 vs. 8, 2 vs. 7, but it isn't guaranteed.
Example from the in-season reveal. (Obviously some of the placements/inclusion already has changed, but for demonstration purpose only)
SOUTH
1 Auburn (1)
2 Texas A&M (6)
3 Wisconsin (11)
4 Texas Tech (13)
(31 total)
MIDWEST
1 Alabama (2)
2 Purdue (7)
3 Iowa State (9)
4 Kansas (15)
(33)
EAST
1 Duke (3)
2 Tennessee (5)
3 Arizona (12)
4 St. John’s (16)
(36)
WEST
1 Florida (4)
2 Houston (8)
3 Kentucky (10)
4 Michigan (14)
(36)
--> Additional detail, as noted on the CBS broadcast, #5 cannot be placed in same region as top overall seed (hence, why A&M is in #1 Auburn region instead of Tennessee).