Here are the matchups for the semifinals of the West Region

NO. 1 GONZAGA (34-1) vs. NO. 4 WEST VIRGINIA (28-8)

Site: SAP Center, San Jose,California.

Time: 4:30 p.m.

TV: TBS

Series: Gonzaga leads 3-0.

How they got here: Gonzaga started slow before running away from a 16 seed in South Dakota State (66-46) and then ended the historic season of Northwestern (79-73). West Virginia earned a hard-fought win against Bucknell (86-80) before never trailing in beating Notre Dame (83-71).

Backcourt: It’s simple. “Press Virginia” needs to rattle the Zags, first taking junior point guard Nigel Williams-Goss out of his game and causing the sort of havoc that has seen opponents wilt under all the turnovers Bob Huggins’ team can create with its in-your-face defense. The guards — Jevon Carter, Daxter Miles Jr. and Tarik Phillip — have been getting it done and then some at both ends for West Virginia. Williams-Goss had an All-America season for the Zags, and the former Findlay Prep standout has averaged 19.2 points in the past five games. He is supported by sophomore Josh Perkins and senior Jordan Mathews. Gonzaga’s season-high in turnovers is 20 against Tennessee. West Virginia opponents average 21. EDGE: West Virginia.

Frontcourt: Przemek Karnowski scored only four points against Northwestern in a Round of 32 victory for the Zags, but anyone who goes 7 feet 1 inch tall and 304 pounds is going to present matchup issues. He’s also rested and ready, having played an average of 18 minutes in two NCAA wins. There are few better defenses nationally than Gonzaga, and it’s likely West Virginia will have more of its shots contested than it has seen this season. Size matters here, and the Zags have more of it with Karnowski, 7-foot freshman Zach Collins out of Bishop Gorman High and forwards Jonathan Williams (6-9) and Killian Tillie (6-10). West Virginia doesn’t start a player taller than 6-9. EDGE: Gonzaga.

Possible unsung hero: Nathan Adrian. The senior has played in 139 games for West Virginia, sixth most in school history, and at 6-9 and 235 pounds, could be one of the few Mountaineers to stand up against the imposing size Gonzaga presents.

Did you know?: Gonzaga ranks first nationally in adjusted defensive efficiency at 87.3 and is the only team nationally among the top 10 in offensive and defensive ratings.

Key stat: West Virginia has forced almost as many turnovers (724) as it has allowed baskets (806).

Bottom line: We haven’t seen the best of Gonzaga this tournament, certainly not the side that has 29 double-digit wins and six against top 25 RPI opponents. But its defense remains stellar and suffocates those launching 3s. The Zags have had ample time to prepare for West Virginia’s press, and as impressive as the Mountaineers were in eliminating Notre Dame, size, defense and a great point guard is usually enough in March. The Zags have all three.

Prediction: Gonzaga 75, West Virginia 67.

NO. 2 ARIZONA (32-4) vs. NO. 11 XAVIER (23-13)

Site: SAP Center, San Jose, California.

Time: Approximately 7:09 p.m.

TV: TBS.

Series: Arizona leads 1-0. The only meeting was two years ago, also in the Sweet 16.

How they got here: Arizona took care of North Dakota (100-82) before struggling to beat Saint Mary’s (69-60). Xavier earned two impressive victories in dismissing Maryland (76-65) and Florida State (91-66).

Backcourt: Xavier starts four guards, but they’re bigger and more physical than you normally see from the position. Things changed when sophomore point Edmond Sumner tore his ACL on Jan. 29, leaving the lead duties to freshman Quentin Goodin. But the Musketeers are back in the Sweet 16 because of junior wing Trevon Bluiett, who is averaging 25 points and has shot 8 of 15 on 3s in the tournament. Arizona doesn’t shoot a ton of 3s, but it needs to make its share against Xavier’s 1-3-1 zone. The Wildcats were good enough against zones from UCLA and Oregon in the Pac-12 tournament, and the trio of Kadeem Allen, Allonzo Trier and Rawle Alkins combine to average 38.0 points, 14.1 rebounds and 7.7 assists. EDGE: Xavier.

Frontcourt: This is where things can get away from Xavier. Tough and physical and again strong on the boards, it’s still better offensively than on defense, where containing Arizona freshman forward Lauri Markkanen (15.8 ppg, 7.2 rpg) could prove overly difficult. Markkanen and center Dusan Ristic have combined to average 61 points in two NCAA games. If the Musketeers can offer the same inside play they did in routing Florida State, this part of the equation becomes much closer. Xavier plays inside-out and is balanced in that no one area seems to be featured over another, but Arizona is at a whole other level. EDGE: Arizona.

Possible unsung hero: Sean O’Mara, Xavier: He needs to continue playing well. The 6-10 junior forward has shined lately on the offensive end, and anyone with size for the Musketeers will be tested defensively against the Wildcats from the opening tip. Xavier is 8-1 when O’Mara scores in double figures.

Did you know?: There are no secrets. Arizona coach Sean Miller arrived in Tucson after five seasons at, yes, Xavier. Chris Mack, his former top assistant with the Musketeers, has led the program to four Sweet 16s.

Key stat: Xavier’s most used lineup consists of one 6-10 player (O’Mara) and everyone else 6-6 or shorter.

Bottom line: March is about matchups, and you shouldn’t compare the struggles Arizona had against Saint Mary’s to how it will fare against Xavier. While the Musketeers have looked terrific in the tournament, they won’t be able to control tempo against Arizona as the Gaels did. Truth is, Saint Mary’s is better than Xavier.

Prediction: Arizona 70, Xavier 62.