The Pac-12 tournament is wide open, unless the top seed dominates.

Arizona is heavily favored to win the four-day event, which begins Wednesday in Las Vegas. But if the Wildcats stumble, chaos will reign.

Remove Arizona from the equation, and you have as much chance of picking the winner at the MGM Grand Garden Arena as you do of beating the house at the MGM Grand Casino.

This is the same conference that played 18 games, only to produce a five-team tie for third place.

It's the same conference that just witnessed its second-place team lose to the 11th-place team by 18 points.

The best reflection of Arizona dominance isn't the three-game gap in the league standings but the projected five-seed gap in NCAA tournament position. The Wildcats are a lock for one of the coveted No. 1s; nobody else looks better than a No. 6.

The Wildcats probably aren't deep enough or gifted enough offensively to blast through three games in three days with nary a hint of trouble.

But they are one of the best defensive teams in league history, with elite guard play and a force of nature on the frontline in former Archbishop Mitty star Aaron Gordon.

Make no mistake: It's in the league's best interest for Arizona to lose this week -- not to UCLA, which is a lock for the NCAAs, but to a team on the March Madness bubble like Cal or Colorado that could use a big win.

For the Pac-12, maximizing its allotment of at-large berths -- each one is worth $250,000 to the league -- is a priority this week.

If the Wildcats stumble, which teams are most likely to grab the title?

It's difficult to have faith in either Cal or Stanford after their ragged play down the stretch.

The fourth-seeded Bears have lost eight of their past 13 and were a basket away from getting swept by Utah and Colorado last weekend.

The sixth-seeded Cardinal has lost three of four and also came harrowingly close to an oh-fer weekend against the Mountain schools.

Both teams are on the bubble; both need to show well in Las Vegas; and both need favorable results from league tournaments around the country. (A spate of upsets could shrink the bubble, knocking out contenders with the most-flawed resumes.)

The situation is highly fluid and preposterously nuanced -- the NCAA selection committee convenes Wednesday in Indianapolis to pick and seed the field -- but at this point it seems Stanford is on the right side of the bubble, Cal the wrong side.

Based on the order-of-finish, UCLA stands as the top challenger to Arizona, the team most capable of derailing the Wildcats on a neutral court.

But the Bruins are hardly an impressive No. 2: They did no better than a split on every league road trip and finished the regular season with a stinker, losing to lowly Washington State by 18 points.

The Mountain schools are as well-coached as any teams in the tournament, and each came within a point of sweeping the Bay Area.

Colorado has figured out how to win without star guard Spencer Dinwiddie, who suffered a season-ending knee injury in mid-January, and Utah has assimilated Delon Wright, a gifted transfer from City College of San Francisco.

Arizona State beat Arizona a month ago, then lost four of its next six. The Sun Devils, like Cal and Stanford, must recover their mid-season rhythm in a hurry.

The best bet might be Oregon, which has won seven in a row, just beat Arizona and possesses enough depth and scoring balance to survive the multi-day event.

There won't be any in-betweens this week at the MGM Grand. Either form holds or total chaos reigns.

For more on college sports, see Jon Wilner's College Hotline at blogs.mercurynews.com/collegesports. Contact him at jwilner@mercurynews.com or 408-920-5716.