N.C.A.A. Tournament: Duke Avoids Upset in Win Over Central Florida

“I feel like a fifth grader who just ate Skittles,” Williams said. “Just want to say that.”

Williams, the Southeastern Conference’s two-time player of the year, dazzled in overtime, scoring six of Tennessee’s first nine points. He also contributed a critical steal for the Volunteers, who will play third-seeded Purdue on Thursday night in Louisville, Ky. It will be their first trip to the round of 16 since 2014, when they crashed the tournament as a No. 11 seed.

This season they have rated among the nation’s best since November, even spending a month as the top-ranked team, but their performance across their two games in Columbus, Ohio, has challenged their standing as a championship contender in a region fronted by Virginia.

Tennessee toted into the tournament painful memories of last season’s exit, when as a No. 3 seed it was upset in the second round by Loyola-Chicago. The Volunteers struggled in a 77-70 first-round victory against No. 15 Colgate, and Coach Rick Barnes said Sunday that he thought his team has carried “a little extra stress” to go deeper this year. That stress seemed absent in the first half against Iowa, when they complemented swarming defense with inside-out balance, racing to a 44-19 lead.

Trailing by 21 at halftime, Iowa opted not to run with Tennessee in the second half. Slowing down the pace, the Hawkeyes fed the ball inside more to Tyler Cook and Luka Garza. Jordan Bohannon’s three free throws — on what seemed a questionable foul call on Lamonte Turner, who appeared to have blocked the 3-point attempt cleanly — tied the score for the first time, at 67-67, with 2:39 remaining, and then Iowa overcame a four-point deficit in the final 58 seconds to send the game into overtime.

Had the Hawkeyes won, they would have matched Brigham Young’s comeback against Iona in 2012.

“We know it’s not going to be perfection — it never is,” Iowa Coach Fran McCaffery said. “But what you hope to get is a perfect effort. And that’s what we got.”

The other three No. 2 seeds — Michigan, Michigan State and Kentucky — won their second-round games by an average of 13.7 points, and only Kentucky was seriously tested, by Wofford. If the Volunteers are to progress to their first Final Four, they must play better than they have across their first 85 minutes of play — and they know it.

“The way we started the game, that’s the team we win,” said Tennessee guard Admiral Schofield. “The way we finished the game, we can’t have that. That’s what got us beat throughout the season. The team you saw in the first half is what won 31 games. We have to be consistent in that aspect. But this time of year, it’s about winning, about surviving and advancing.”