Upsets were hard to come by in the second round of the NCAA men's basketball tournament.

Fifteen of the 16 lower seeds in the second-round matchups advanced to the Sweet 16 to set up six matchups between top five seeds.

The only outliers are sixth-seeded Clemson and 11th-seeded NC State, both of whom are power-conference teams from the ACC.

Upsets by seed line should happen at some point on Thursday and Friday, but they will not be the surprising type of upset we typically see during March Madness.

A majority of the 16 teams remaining could make a strong case to win the national championship and that should make the Sweet 16 the best round yet in terms of competition.

Sweet 16 Schedule

Thursday, March 28

West Region: No. 6 Clemson vs. No. 2 Arizona (7:09 p.m. ET, CBS)

East Region: No. 5 San Diego State vs. No. 1 UConn (7:39 p.m. ET, TBS/truTV)

West Region: No. 4 Alabama vs. No. 1 North Carolina (9:39 p.m. ET, CBS)

East Region: No. 3 Illinois vs. No. 2 Iowa State (10:09 p.m. ET, TBS/truTV)

Friday, March 29

South Region: No. 11 NC State vs. No. 2 Marquette (7:09 p.m. ET, CBS)

Midwest Region: No. 5 Gonzaga vs. No. 1 Purdue (7:39 p.m. ET, TBS/truTV)

South Region: No. 4 Duke vs. No. 1 Houston (9:39 p.m. ET, CBS)

Midwest Region: No. 3 Creighton vs. No. 2 Tennessee (10:09 p.m. ET, TBS/truTV)

No. 3 Illinois over No. 2 Iowa State

A No. 3 seed upsetting a No. 2 seed in the Sweet 16 is hardly viewed as shocking based on seed number alone.

However, the Iowa State Cyclones have played more like a No. 1 seed and currently look like the biggest challenger to the UConn Huskies to reach the Final Four from the East region.

Iowa State is 9-1 in its last 10 games and it has not allowed an opponent to score over 65 points during that stretch.

The Illinois Fighting Illini will test that statistic with the top-rated offense in KenPom's adjusted efficiency metric.

Illinois scored over 70 points in all but one of its 28 victories this season and it eclipsed the 80-point mark in each of its last four victories.

The Illini will take a step up in opponent on Thursday since it beat a pair of mid-major sides to reach the Sweet 16, but they can hang with the Cyclones for a few reasons.

Illinois owns the superior offensive rebounding and free-throw shooting totals in the matchup with Iowa State and it was competitive in its four games against Sweet 16 foes (Purdue twice, Marquette and Tennessee) this season.

Iowa State allowed over 70 points in six of its seven defeats this season, so the blueprint is there for Illinois to capitalize on.

The Illini must play at their pace and take Iowa State out of its comfort zone to likely set an Elite Eight date with UConn on Saturday.

No. 5 Gonzaga over No. 1 Purdue

The Gonzaga Bulldogs are one of the few teams left in the NCAA tournament equipped to pull off an upset of Zach Edey and the Purdue Boilermakers.

Gonzaga has enough size across its front line to at least slow down the Purdue big man's threat.

Graham Ike, Anton Watson and Ben Gregg can rotate the defensive responsibilities so that the Zags are not mired in foul trouble after the first few minutes. They also have experience defending the 2023-24 version of Edey from their November 20 matchup at the Maui Invitational.

Mark Few has dealt with his share of unique matchup challenges over his three Elite Eight trips in the last five seasons.

Gonzaga slowed down a deep and long Florida State team with three future NBA players on its roster to reach the final eight in 2019. It also took down an experienced UCLA squad in last season's Sweet 16.

Few holds a coaching advantage over Matt Painter, who has only been past the Sweet 16 once in his career with the Carsen Edwards-led team in 2019.

Purdue could control the contest through Edey, like it did in the first two rounds, but that might be tough against Gonzaga's 10th-rated two-point defense.

The Boilermakers could outclass Gonzaga from three-point range, but it is worth noting the Zags outshot Kentucky, the No. 2 three-point shooting team, in a road win on February 10.