NCAA tournament viewing guide: What, when and where to watch Round 2

Sweet 16 berths are on the line in Saturday's March Madness action. And there's plenty of intriguing matchups to watch, like Arizona vs. St. Mary's and Purdue vs. Iowa State.

The first round of the madness is in the books, and believe it or not, more than half (32 of 63) of the games in the 2017 NCAA tournament have already been played. Saturday's Round of 32 contests present a bunch of intriguing matchups and storylines. Here's what to watch for, when half of the Sweet 16 will be set.

(All times Eastern)

12:10 p.m., CBS
West Regional: No. 4 West Virginia vs. No. 5 Notre Dame

Both of these teams were tested in their first-round games; Bucknell hung with West Virginia, while Princeton missed a potential game-winner with under five seconds to go. This is a classic strength-vs.-strength matchup. West Virginia's relentless press defense forced the most turnovers per game of any team during the regular season, while Notre Dame's average of 9.3 turnovers per game is the lowest in the country. If the Fighting Irish don't improve from their performance against the Tigers, West Virginia will advance.

2:40 p.m., CBS
East Regional: No. 1 Villanova vs. No. 8 Wisconsin

Before the season, when Villanova was ranked No. 4 and Wisconsin was No. 8, this seemed like it could have been a Sweet 16 or even an Elite Eight matchup. The Wildcats let Mt. St. Mary's hang around before pulling away in the second half of their tournament opener, while the under-seeded Badgers got an impressive win over a talented Virginia Tech team. Will Wisconsin's Nigel Hayes be able to contain Wooden Award Finalist Josh Hart (18.7 points, 6.5 rebounds)?

5:15 p.m., CBS
West Regional: No. 1 Gonzaga vs. No. 8 Northwestern

Forgive us if you've heard this before, but Northwestern is making its first-ever appearance in the NCAA tournament. The Wildcats benefited from a mind-boggling mistake from Vanderbilt's Matthew Fisher-Davis, who intentionally fouled Northwestern's Bryant McIntosh with 15 seconds remaining and the Commodores up one. All the pressure in this matchup is on Gonzaga, which has struggled to turn its regular-season success into deep NCAA tournament runs. Keep an eye on the big men—Northwestern's Dererk Pardon (8.7 points, 8.1 rebounds, one miraculous buzzer-beater) will have to stay out of foul trouble, as he's the only defender the Wildcats have who has the potential to contain Gonzaga's 7'1'' Przemek Karnowski.

Cursed No More: Scene from Northwestern's first-ever NCAA tournament victory

6:10 p.m., TNT
West Regional: No. 3 Florida State vs. No. 11 Xavier

Florida State held off its pesky in-state neighbor Florida Gulf Coast to clinch a berth in the second round, while Xavier's Trevon Bluiett had 21 points and outplayed his point guard counterpart Melo Trimble to help the Musketeers get past No. 6 seed Maryland. Florida State has a big size and athleticism advantage here, and Xavier came into the tournament having lost seven of 10.

No. 11 Xavier knocks off No. 6 Maryland behind Trevon Bluiett's big second half

7:10 p.m., TBS
South Regional: No. 4 Butler vs. No. 12 Middle Tennessee State

Butler was impressive in its first-round win over Winthrop, but the Middle Tennessee present a different challenge all together. This is the Blue Raiders' second consecutive appearance in the second round—they upset Michigan State as a No. 15 seed last year—and don't let the seed fool you, this team has won 11 in a row and is a dangerous proposition for any opponent. Butler would do well to get another stellar shooting performance from senior guard Avery Woodson, who hit 6 of 10 threes in the Bulldogs' opener.

Middle Tennessee looks to continue its tournament magic against Butler

7:45 p.m., CBS
West Regional: No. 2 Arizona vs No. 7 Saint Mary's

Saint Mary's has four losses on the season...and three of them came against Gonzaga. This is a quality (and heavily Australian) Gaels team that can flat out defend; Randy Bennett's team allows the second fewest points per game of any team in the country. It's also fourth in assist-to-turnover ratio. But when Arizona's Allonzo Trier (17.3 points, 5.1 rebounds) is playing as well as he is right now, the Wildcats are tough to beat.

8:40 p.m., TNT
East Regional: No. 4 Florida vs. No. 5 Virginia

Both of these teams struggled in their respective first-round matchups, but surviving and advancing is all that matters, so mission accomplished. This probably won't be a game for lovers of offense, as Florida is fourth in adjusted defensive efficiency and Virginia is second (and first in points allowed per game). The first team to 60 will almost certainly win, and if the Gators can get another 20-plus point performance from Devin Robinson, that should send them to the Sweet 16 for the first time since 2014.

9:40 p.m., TBS
Midwest Regional: No. 4 Purdue vs. No. 5 Iowa State

Nevada was a popular pick to upset Iowa State, but the Cyclones jumped out to an early lead and hung on. One problem now: Iowa State doesn't play anyone bigger than 6'8'', so Purdue's Caleb Swanigan (18.4 points, 12.6 rebounds) could have a huge game. He has 27 double-doubles on the year, jus three shy of Blake Griffin's record for a major conference player in the past 20 years. The Cyclones will almost certainly be forced to double-team Swanigan, which should free up the Boilermakers' shooters.