Led by Richardson and senior guard Jordan McRae’s game-high 20 points, four starters finished in double figures for Tennessee (22-12), which advances to face No. 6 seed Massachusetts in a Midwest Region second-game Friday in St. Louis.
Junior forward Jarnell Stokes added 18 and senior guard Antonio Barton marked 10 to give the Volunteers their first tournament win since an Elite 8 appearance in 2010.
For Iowa (20-13), the game followed the same frustrating trajectory as its season.
The Hawkeyes started the year fast, ascended to a No. 10 national ranking and then lost six of their last seven games heading into the tournament.
Rallying around McCaffrey’s return Wednesday night, Iowa started as well as it could have hoped, holding Tennessee without a basket for the first six minutes while jumping out to a 16-4 lead. But the Hawkeyes missed 11 of 16 shots in the final six minutes of regulation and all eight of their attempts in overtime.
Sophomore center Adam Woodbury led Iowa with 16 points.
In the first game of the night, Cal Poly made history by becoming the first 19-loss team since 1955 to win a tournament game as the Mustangs knocked off Texas Southern 81-69 in a battle of Midwest Region 16 seeds.
Making its first tournament appearance in program history, Cal Poly hit 10 of its first 14 shots and led for the final 33 minutes to advance to a Midwest Region second-round game Friday in St. Louis against undefeated No. 1 seed Wichita State.
The Mustangs (14-19) are the 23rd team with a losing record to qualify for the tournament, and they are the first to advance since Oakland posted an opening-game win at UD Arena in 2005.
Senior forward Chris Eversley scored 19 points and sophomore forward Dave Nwaba added 17 as Cal Poly shot a season-high 57 percent (29 of 51) from the floor.
Senior center Aaric Murray scored a game-high 38 points for Texas Southern (19-15), but the rest of the team was just 10 of 27 for 31 points.
Quotable: "It was a day that, needless to say, has been very difficult," McCaffrey said. "I got up at 5 a.m. and we had Patrick at the hospital at 6. He's getting prepped for surgery on his neck to remove a tumor, and you're talking about potential malignancy and things of that nature and you're saying to yourself: Wow, it puts wins and losses in perspective."
Quotable II: "Maybe sounds arrogant, but I did (believe this could happen)," Cal Poly coach Joe Callero said. "I completely believed in our players the entire time. And now we go play a No. 1 seed and get more national recognition for Cal Poly. Our kids deserve it. This is special because of the institution. Such a high academic institution. And sometimes people look like, oh, you just got a bunch of smart kids out there; you can't get to the tournament. It's been 20 years. Cal Poly has been Division I for 20 years, and now we will have two more days of national exposure for Cal Poly."
Wednesday's star: In addition to scoring 17 second-half points after going 0 for 5 in the first half, Richardson limited Iowa star Roy Devyn Marble to less than half of his 15.9-point average with seven points on 3 of 16 shooting, including 0 of 6 from 3-point range.
Crowd count: Wednesday's games drew 11,534 fans to UD Arena after 12,077 showed up for Tuesday's contests for a two-day total of 23,611. Last year's event attracted 24,245. Those numbers could play a key role when it comes time for the NCAA to decide whether to keep the First Four in Dayton when the current contract expires after next season.
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