Which Number One Is True Number One?

With four No. 1 seeds in the Final Four for the first time ever, it's tough to find major holes in any of the contenders for the national championship.

Still, each team brings different strengths to the table, creating some interesting contrasts and some compelling matchups. Let's take a look at the four combatants, and the factors that could make or break their chances:

UCLA

STAR PLAYER: Kevin Love. The freshman big man has ripped through everyone in this tournament, averaging 21.8 points and 11 rebounds a game while shooting nearly 62% from the field and better than 77% from the free-throw line. All three of the other Final Four teams can challenge Love with one or more aggressive defenders in their frontcourt. If Memphis' Joey Dorsey can contain Love in Saturday's semifinal game, the Tigers will have a great chance of knocking UCLA out of the tourney.

X-FACTOR: Josh Shipp. His ability to find his shooting stroke could decide whether or not the Bruins hang another championship banner. Shipp shot just 2-for-14 from behind the three-point line in the tournament. Against lesser opponents, UCLA can get away with Love, Darren Collison and Russell Westbrook carrying the scoring load while the defense does the rest. They need Shipp contributing if they want to beat any of these teams.

THEY'LL WIN IF…: They limit turnovers and control the tempo. The other three Final Four teams all like to play fast. Memphis in particular applies pressure defense all over the court, and depends on transition baskets to go on big runs and blow teams out. UCLA will still look to push the ball when it can, especially with Love throwing the best outlet passes in the game. But it must do so judiciously, while taking care of the ball, to win.

THEY'LL LOSE IF…: Darren Collison gets outplayed at the point. Collison's battle with Memphis's Derrick Rose — the potential No. 1 pick in this year's NBA draft — should be fascinating to watch. Rose asserted himself against Texas, snatching rebounds a foot above the rim, leading the break and driving to the rim. A Collison-Ty Lawson pairing in a potential championship game against North Carolina would be equally compelling.

MEMPHIS

STAR PLAYER: Chris Douglas-Roberts. Rose gets the ink as the super prospect, but Douglas-Roberts is the team's leading scorer and more consistent player. He's at his best slashing to the basket and scoring on the break, meaning opponents have to get back in transition defense and seal his driving lanes in the half-court set to contain him.

X-FACTOR: Joey Dorsey. He has been either very good or very bad throughout the regular season and into the tournament. Against Mississippi State in the second round and Texas in the Elite Eight, Dorsey sprang for a combined 24 points, 24 rebounds, and seven blocks. In the other two games: nine combined points, 13 rebounds, and three blocks. If he plays at peak intensity, Memphis is a beast to beat. If he mails it in, UCLA's Kevin Love will hand him his lunch and the Tigers will wonder what might have been.

THEY'LL WIN IF…: They force turnovers and score points off the break. The Tigers don't have any true post-up threats and are erratic behind the three-point line, especially in their half-court offense. When they're running, Memphis' army of athletes can pound dunks on people's heads all day long.

THEY'LL LOSE IF…: They're tied late in a game or in overtime. In those situations, free throws and executing offensive plays usually decide the outcome. The Texas game notwithstanding, those are still Memphis' two Achilles heels.

KANSAS

STAR PLAYER: None. Brandon Rush is the best known of the bunch and the best NBA prospect. But this Kansas team spreads the wealth. Many see that diversity as a weakness, a sign that there's no go-to guy to rely on when the chips are down. I don't buy it. Just ask Davidson what happens when you put all your trust in one player with the game on the line, and with no contingency plans.

X-FACTOR: Rush. He has the talent to take over a game on both ends, with quick feet and long arms on defense and a combination of superior court vision and a smooth jumper on offense. Coach Bill Self often yells at Rush to shoot more and not be afraid to take over. There's nothing wrong with giving opportunities to his talented teammates. But Rush needs to strike a balance between teamwork and being too deferential.

THEY'LL WIN IF…: They play the kind of defense they played against Davidson. Yes, the Jayhawks were one Jason Richards heave away from going home early. But they also showed they could frustrate a red-hot scorer in Stephen Curry. They'll need to do the same against North Carolina's Tyler Hansbrough, Ty Lawson, and Wayne Ellington, not to mention the winner of the UCLA-Memphis game if they make it to the finals.

THEY'LL LOSE IF…: They don't execute on offense. Even with a great defensive effort, North Carolina's going to score their share of points. The Jayhawks need some combination of dribble penetration from Russell Robinson, Mario Chalmers, and Sherron Collins, points inside from Darrell Arthur, Darnell Jackson and Sasha Kaun and good perimeter shooting from Rush if they're going to knock off the Tar Heels.

NORTH CAROLINA

STAR PLAYER: Tyler Hansbrough. If Hansbrough continues to knock down 17-foot jumpers the way he did against Louisville, he becomes that much tougher to defend. Another underrated part of Hansbrough's game is his ability to get to the free-throw line. Knowing you have a player who can either score or get fouled more often than not when he makes a move inside is a great safety to have against an elite opponent.

X-FACTOR: Wayne Ellington. Like UCLA's Josh Shipp, he's an explosive scorer when he's on and a ghost when he's not. When Ellington's making threes and point guard Ty Lawson is healthy, this team is nearly unbeatable.

THEY'LL WIN IF…: Either he or Collison is the fastest point guard in the country with the ball in his hands. Once in the lane, Lawson can kick out to open shooters for threes, dish to big men inside for layups or go all the way to the goal himself. Now 100% after battling injuries this season, he's a threat on every possession.

THEY'LL LOSE IF…: Hansbrough gets in foul trouble. This is a deep team, and fellow Tar Heel big men Deon Thompson and Alex Stepheson have looked very good at times. But if big men for Kansas or UCLA can get Hansbrough out of the game early, everything changes in an instant.

Mr. Keri (jonahkeri@gmail.com) is a writer for ESPN.com's Page 2.