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Let the madness officially begin. With a flurry of close contests and even some upsets, the college basketball regular season ended over the weekend and paved the way for the start of the conference tournament barrage.

But before we get to all of that, The Associated Press checked in one last time and assessed how the nation's best stack up. Kentucky finished its 31-0 regular season with a wire-to-wire lead atop the standings, receiving all 65 first-place votes. Duke closes in second place, while Virginia drops to No. 3. No. 4 Villanova and No. 5 Arizona also stay firm to close out the Top Five.

Here is a look at how the entire Top 25 played out:

Associated Press Rankings: Week 18 Rank Team 1 Kentucky (65) 2 Duke 3 Virginia 4 Villanova 5 Arizona 6 Wisconsin 7 Gonzaga 8 Maryland 9 Kansas 10 Northern Iowa 11 Notre Dame 12 Wichita State 13 Iowa State 14 Louisville 15 Oklahoma 16 Baylor 17 Utah 18 West Virginia 19 North Carolina 20 SMU 21 Arkansas 22 Butler 23 Georgetown 24 Davidson 25 Boise State AP.org

Losses within the strata of the ranked over the last week were plentiful. Fourteen teams dropped at least one contest, and though a majority of those were against one another, the games still provided a telling look into how March may play out.

Virginia, which had worn a cloak of near-invincibility all season, dropped its first road game in a nail-biter against Louisville Saturday. The Cavaliers allowed a shaky Cardinals offense to make nearly half its shots and watched as forward Montrezl Harrell physically dominated his way to 20 points and 12 rebounds. Center Mangok Mathiang gave Louisville a 59-57 victory by draining a jumper with 2.7 seconds remaining.

"I was just shocked that I made it," Mathiang told reporters. "I was running, then Trez came, hugged me and everybody was around me. This is a real big deal."

Barring a surprise early exit from the conference tournament, this loss should do little to push Virginia away from a No. 1 seed. The team's only regular-season losses were against Duke and Louisville, the former a legitimate title contender and the latter one of the country's best defensive teams.

The same cannot be said for Wichita State, which may have cost itself with a loss to Illinois State. ESPN.com's Joe Lunardi currently has the Shockers in a dreaded No. 5 vs. No. 12 matchup. Northern Iowa ultimately took the Missouri Valley Conference tournament championship.

“I have no idea,” Wichita State coach Gregg Marshall said of his team's seeding, per Paul Suellentrop and Tony Adame of The Wichita Eagle. “They pay Joey Brackets (Lunardi) and Jerry Palm…they pay those guys to do that. And they have a lot of big executives that sit on that NCAA (selection) committee to make the high-dollar decisions. My job is just to get in and be a part of the party.”

Also at the mercy of the committee is Murray State, which drops from the Top 25 this week after a one-point loss to Belmont in the Ohio Valley Conference title game. Bruins guard Taylor Barnette drained a three-pointer with 3.2 seconds remaining, giving Belmont an upset victory that sends the Racers' tournament chances into flux.

The Ohio Valley is typically a one-bid conference, and Murray State did little in nonconference play to help its stock. Blowout losses to Xavier and Valparaiso, along with close defeats to Portland and Houston, didn't do much to show what this team could do on a national level. Ken Pomeroy's advanced metrics ranked Murray State's nonconference slate No. 242 in terms of strength.

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"The one thing I will say, is this is an NCAA Tournament team," Murray State coach Steve Prohm said, per SportsNetwork.com (via FoxNews.com). "We're very deserving; if you've watched us play then you would agree. I hope we get a chance, these guys deserve it, but if not we'll be gracious about it and play as a No. 1 seed in the NIT."

Murray State is the only team ranked last week in danger of missing the tournament altogether, but a few others probably wish they could take some things back. Utah is 3-3 in its last six games after a season-closing loss to lowly Washington, Wisconsin's abject thumping of Ohio State is a good sign we can stop taking the Buckeyes seriously and LSU halted Arkansas' late-season ascent to stealth contender.

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Individually, these losses don't mean much. Viewed through a larger prism, they're disconcerting.

Utah's best win came at home in overtime against Wichita State; the Utes are a combined 2-5 against the RPI Top 50, per ESPN. Ohio State cannot score regularly and had one of the weakest nonconference schedules in America. Arkansas' smoke-and-mirrors defense can be just as bad as its offense is spectacular.

To be fair, we probably could have picked any three teams in the middle of the standings. College basketball, perhaps more than any season in recent memory, is extremely top-heavy. Beyond Kentucky, Duke, Arizona, Virginia and Wisconsin, few teams feel like legitimate title contenders. The likes of Villanova, Gonzaga and Kansas have fine resumes but also deep flaws that make them vulnerable in postseason play.

For the first few rounds, that uncertainty should make for a truly mad March. But as we've seen for nearly the entire regular season, the kings stay the kings near the top.

Follow Tyler Conway (@tylerconway22) on Twitter.