SALT LAKE CITY -- Kelly Olynyk scored 17 of his 21 points in the second half and Kevin Pangos hit a late clutch 3-pointer to help No. 1 seed Gonzaga survive a scare from 16th-seeded Southern with a 64-58 victory on Thursday.
Pangos finished with 16 points, including a dagger of a 3-pointer that gave Gonzaga a 62-58 lead with 1:57 remaining. Pangos then helped the Zags avoid being the first No. 1-seeded team to lose to a No. 16 squad by hitting two free throws with 14 seconds remaining.
Southern (23-10) had to remind Gonzaga (32-2) of its old self by nearly pulling off the huge upset in this first-round game.
Derick Beltran scored 21 points and played a key role in helping Southern go on a 12-2 run late in the second half. Yondarius Johnson got the comeback going, hitting a 3-pointer with 8:13 to go after Olynyk's strong second half put Gonzaga up 52-42.
Beltran then scored seven straight points before Brandon Moore tied it at 54-54 with 4:08 remaining with two free throws.
Gary Bell Jr. drained a 3-pointer to put the Zags up by three, but Gonzaga couldn't shake the SWAC champions.
Beltran got Southern back within one point after two free throws with 2:28 remaining before Pangos hit his key 3-pointer.
Malcolm Miller's 3-pointer rimmed out with 1:20 remaining for Southern, and the Zags escaped down the stretch to avoid the stunner.
Gonzaga will play No. 9 Wichita State on Saturday.
Oregon 68, Oklahoma State 55
SAN JOSE -- The Oregon Ducks picked up right where they left off in the Pacific-12 Conference tournament last weekend, parlaying a stingy defense with dominance on the backboards to a stun stunning victory in the Midwest Regional second round at HP Pavilion.
The Ducks, who earned just a No. 12 seed in the region despite having tied for second in the Pac-12 regular season before sweeping to the conference tournament title, advance to a third-round matchup Saturday in San Jose against fourth-seeded Saint Louis, a 64-44 winner over New Mexico State earlier in the day.
Iranian-born senior forward Arsalan Kazemi recorded an 11-point, 17-rebound double-double, helping the Ducks (27-8) to a 44-32 board advantage and a 12-6 margin in second-chance points against the fifth-seeded Cowboys.
Marquette 59, Davidson 58
LEXINGTON, Ky. -- Vander Blue hit a running lay-up with one second left completing Marquette's comeback win in a second-round game of the East Regional at Rupp Arena.
Davidson's De'Mon Brooks threw the ball away with 6.7 seconds left and a one-point lead, and Marquette was given a final shot. Jamil Wilson inbounded the ball to Blue near midcourt with five seconds remaining, and Blue drove all the way to the basket on Davidson's Jake Cohen.
Blue, a 6-foot-4 guard, went to his left and got the ball off the backboard just over Cohen, who is 6-10.
Davidson (26-8) had won 17 games in a row, which was the longest active winning streak in the country.
Blue hit a 3-pointer with 28 seconds left to bring Marquette within two points, but Nik Cochran answered with two free throws for the Wildcats.
Memphis 54, St. Mary's 52
AUBURN HILLS, Mich. -- Joe Jackson had 14 points, seven assists and six rebounds as sixth-seeded Memphis barely won in the Midwest Region at The Palace.
Matthew Dellavedova of St. Mary's missed a 3-pointer at the buzzer after Jackson's turnover with 1.9 seconds left.
Memphis' defense keyed the victory, as the Tigers blocked 12 shots, including eight by D.J. Stephens, and had nine steals. Tarik Black supplied 12 points and seven rebounds and Adonis Thomas added 12 points for the Tigers, who led by 15 in the first half and hung on down the stretch.
Dellavedova, an 86 percent free throw shooter, missed two from the line in the final minutes, including the front end of a 1-and-1 with 4:16 left.
Jackson hit a 3-pointer at the other end and Memphis scored five consecutive points to lead, 49-40, getting just enough breathing room down the stretch.
Wichita State 73, Pitt 55
SALT LAKE CITY -- Guard Malcolm Almstead scored 22 points and reserve forward Cleanthony Early had 21 points to lead Wichita State to a surprisingly one-sided victory.
While getting a pair of 20-point games was an offensive boost for the ninth-seeded Shockers, it was their stingy defense that pushed them into the next round.
Wichita State held eighth-seeded Pittsburgh scoreless for nearly six minutes spanning the end of the first half and the beginning of the second half.
The Shockers went on an 11-0 run in that period and then sealed the win with a dominating 15-5 surge, which included a Tekele Cotton steal and slam and five points from Armstead.
Saint Louis 64, New Mexico State 44
SAN JOSE, Calif. -- Dwayne Evans poured in 24 points, including 16 in a first half in which he equaled New Mexico State's total, as Saint Louis used suffocating defense early and an opportunistic offense late while cruising in the Midwest Regional at HP Pavilion.
The Billikens' 16th victory in their last 17 games advanced them to a third-round matchup Saturday in San Jose against the winner of the Oklahoma State-Oregon game.
Evans, the Most Outstanding Player of last week's Atlantic-10 Conference Tournament in Brooklyn, got inside the New Mexico State zone defense for three open jumpers just inside the free-throw line, accounting for six of his 16 first-half points and helping the Billikens (28-6) run off to a 29-16 halftime advantage.
Butler 68, Bucknell 56
LEXINGTON, Ky. -- Butler relented from its trademarked tight defense in the second half, but the Bulldogs took off the kid gloves and finished strong for a victory in the East Regional.
The Bulldogs (27-8), seeded sixth, allowed Bucknell to make a 17-2 run and take a 37-33 lead midway through the second half, but Butler answered with two quick 3-pointers to retake a lead, 39-37.
Those deep bombs, and the second was Rotnei Clarke's shot from NBA range, were unusual because they were the Bulldogs' 3-point baskets of the game, as Butler missed its first 13 tries from behind the arc.
The Bison (28-6), seeded 11th, stayed in the game, but Butler's 10-0 run gave the Bulldogs a 53-42 lead with 2:19 to play.
Clarke finished with 17 points to lead Butler. In last game at Rupp Arena, as a member of the Arkansas Razorbacks, he scored 26 points in a 77-76 overtime win over Kentucky on Feb. 23, 2011.
Michigan State 65, Valparaiso 54
AUBURN HILLS, Mich. -- Senior center Derrick Nix powered for 23 points and 15 rebounds and Michigan State scored 14 unanswered points in the first half as the third-seeded Spartans cruised in their Midwest Region opener at The Palace.
Keith Appling had 15 points and six rebounds for third-seeded Michigan State (26-8), which plays the survivor of Thursday's Memphis-St. Mary's game in the third round on Saturday. Freshman Gary Harris chipped in 10 points, four rebounds and four assists for the Spartans, who led by as much as 27.
Making their first NCAA Tournament appearance since 2004, Valparaiso (26-8) couldn't recreate the magic of their 1998 run when current coach Bryce Drew hit an iconic buzzer beater to defeat Ole Miss. The Horizon League champion Crusaders, who were led by Ben Boggs' 15 points and Erik Buggs' 14, shot just 35.2 percent from the field.