It's the Sweet 16 - the second week of the NCAA Tournament - and that means bragging rights for college basketball programs.

Check the cover of media guides or banners adorning arenas. They always start with Sweet 16 appearances. No bragging about the first weekend. Playing this week means you had two good wins and you are just two wins from the Final Four.

The story of the tournament has been Kentucky's pursuit of a perfect season. Everyone's playing in that shadow. The Wildcats improved to 36-0 - the best start to a season for any team - and they're trying for 40-0. That would be the first undefeated season by a national champion since Indiana in 1976.

The East Region changed dramatically entering the Sweet 16 with top seeds Villanova and Virginia ousted. It's only the eighth time that the top two teams from one region failed to advance to the second week. The last time that happened was in 2004.

The Atlantic Coast Conference and Pac-12 entered the round of 32 as the only leagues with three or more teams not to lose a game. Virginia's loss to Michigan State was the ACC's first after a 9-0 start, and Oregon faced Wisconsin with a chance to make the Pac-12 8-0.

Here are some storylines to watch as the Sweet 16 approaches:

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UCLA'S RUN: The Bruins were the at-large team complained about the most on Selection Sunday. Wins over SMU and UAB have the 11th-seeded Bruins in the Sweet 16 for the second straight year, the first time they have done that since reaching the Final Four in three straight seasons between 2006 and 2008.

"The selection committee thought we were good enough to play in this tournament, and I think we proved it," forward Tony Parker said.

They will face the winner of the Gonzaga-Iowa game in the Sweet 16.

"There's no better time to do that than March," UCLA coach Steve Alford said.

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OLD TEAMS: Arizona coach Sean Miller will face his former school, Xavier, in the Sweet 16. Miller has taken the second-seeded Wildcats to the regional semifinals for the third straight year.

Now, he will face the sixth-seeded Musketeers, whom he coached from 2004-2009. Xavier reached the Elite Eight in 2008 under Miller and the Musketeers were in the Sweet 16 the next year.

Chris Mack succeeded Miller at Xavier when he left for Arizona.

"As far as playing Sean, it's really tough," Mack said. "I recruited all these guys that play for me. But Sean gave me a heck of an opportunity to come back to my alma mater. He put a lot of responsibility and trust in me. He ultimately really pushed for me to become the head coach, and for that I'm eternally grateful. It's hard to play against one of your best friends in the business. But it really won't matter to our guys, nor will it matter to Arizona, because they don't know me from a bucket of paint."

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SPARTY'S PARTY: Michigan State under Tom Izzo has become as familiar in the Sweet 16 as the guys in a school band wearing enough face paint to cover a garage.

The Spartans have reached the regional semifinals for the seventh time in the last eight years. They will face the Oklahoma-Dayton winner in Syracuse, New York.

Izzo has a 13-1 record in games in the round of 32. He was surprised a bit that this team won its second game to move on.

"We've been a team all year that has banged around, probably lost more games than we should have just because of the free throw situation or dumb coaching with 2, 3 seconds left to go in the game and people hitting 3s and tying it," Izzo said. "But I think we've had to earn every single thing we've gotten because every game's been like that. So I think they felt comfortable in a game because that's the way not their whole tournament has gone or the Big Ten Tournament, their whole season has gone that way. I'm really proud of this team. I don't use that word lightly when I speak and I am."

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IRISH ALIVE: For the first time in 12 years Notre Dame is in the Sweet 16 and the Fighting Irish moved on with an overtime win over Butler. Steve Vasturia had 20 points for the third-seeded Irish, who face the winner of the Kansas-Wichita State game in the Midwest Regional in Cleveland.

"It's a great feeling. We're playing really well right now," Vasturia said. "We made big plays down the stretch, and we've been doing that all year, getting big defensive stops, hitting shots. So it's a great feeling. We're playing with a lot of confidence right now so we want to keep it rolling."

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KENTUCKY'S CHASE: The top-ranked Wildcats showed in the round of 32 why they are the even-money favorite to win the whole thing.

In their win over Cincinnati, the Wildcats shot just 37 percent and were outrebounded 45-38. There really wasn't a point in the game when Kentucky felt threatened about its winning streak and the 64-51 win was the Wildcats' 29th of 36 by at least 10 points.

"I always like it when my team shoots 37, 36, 35 percent and wins in double digits," Kentucky coach John Calipari said. "It shows them they don't have to make shots to win. You can miss them all. No, you can't miss them all. You can miss most of them, and you can still win games if you defend, you rebound and you play that way, make your free throws, and they did."

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