The Blazers of UAB used hot-shooting to overcome a 13 rebound deficit and defeat the 8th-seeded Charlotte 49ers.
UAB, which had lost to Charlotte by 20 earlier in the season, was led by Eric Bush and Mo Finley who combined for 31 (79.4%) of the Blazers' 39 first-half points.
The Blazers also forced Charlotte into 21 turnovers, while only committing nine.
"That was a remarkable turnaround," said UAB head coach Mike Anderson. "Our defensive intensity was the best its been all year long. We were able to get the tempo going the way we wanted it."
UAB will face top seeded Marquette in the second round at 7:00 p.m.
Southern Miss 63 Cincinnati 61
In the game that most expected to be the most lopsided of the first round, Southern Miss battled even with the 5th-seeded Bearcats all night long.
Jasper Johnson tipped in an offensive rebound with 3.8 seconds remaining to give the Golden Eagles the upset victory.
Southern Miss, who had not played Cincinnati this season, was led by Greg Johnson with 21 points.
"I'm really happy for our guys," said Southern Miss head coach James Green. "With the effort we gave tonight I think we really grew up out there. We had players making plays both offensively and defensively and guys stepped up when we needed them."
The 12th-seeded Golden Eagles will face 4th-seeded Saint Louis in the second round at 9:30 p.m.