According to a paper published in 2005, and restated in The Numbers Game by Chris Anderson and David Sally, soccer is the most competitive sport, with upsets happening 45.2% of the time. Add in the chaos of the NCAA tournament and that 45.2% feels like a when, not an if. No one has more to lose than the four number one seeds. And no one is playing with house money more than the teams tapped to play them in the first round. So which number one seed is the most vulnerable to a shock upset? Well, let’s look at the matchups.

Notre Dame

The Fighting Irish are the no.1 seed overall. They have just two losses all season, a 1-0 loss to Pitt, in the last game of the regular season and a penalty kick loss to Stanford in the ACC Championship. Now, Notre Dame takes on UIC, a team that’s 8-7-6 and earned the autobid with a penalty kick win in the Missouri Valley Conference Championship.

Does UIC have a defense that can stop Izzy Engle? That task is going to be easier than finding the offense to outfire-fight Notre Dame. UIC concedes almost as many goals as they score, making this an uphill battle against a Notre Dame side out for revenge. It’s not that the Fighting Irish are invincible, it’s that, with just the one loss in regulation, there’s no way to tell if Pitt's gameplan is the roadmap to victory or if it was just enough to defeat the Irish that once. UIC could upset Notre Dame with a well placed set piece, as Pitt did, but they’ll have to play the relentless defense–a tall order. The key to an upset here is to bait the Irish into frustration and then strike on the counter, forcing fouls and garnering time wasting set pieces.

Stanford

Stanford seemingly has it all: a regular season title, the ACC Championship, one loss all season, and a no.1 seed heading into the NCAA tournament a year after making it to the College Cup. Now, the Cardinal takes on Cal Poly in their first round match up. Cal Poly has a record of 10-2-9 and made the tournament with a 1-0 win in the Big West Championship.

This intrastate matchup has the most potential for an upset. Stanford, riding high, plays on paper the strongest of the teams going against no.1 seeds. In this case, a high flying offense in Stanford meets a team that plays their best soccer against their toughest opponents. Like Notre Dame, there’s not a lot of data on how to upset the Cardinal, except play a perfect game like UCLA did in their 2-0 win. On the other hand, Cal Poly fights fire with fire, demonstrating over the season their ability to match high-scoring offenses with their own burst of goals. If the defense can keep the score within one, then count on Cal Poly’s offense to find a way to take the game to extra time…or even find a way to sneak in a game winner.

Vanderbilt

The lone no.1 seed not from the ACC, Vanderbilt won the SEC Title on penalty kicks. The Commodores have a 15-3-2 record, with two of their three losses coming to ranked opponents. They match up with Tennessee Tech, a team with a 7-6-8 record and an autobid courtesy of a 2-0 win over Lindenwood in the Ohio Valley Conference Championship.

This will be the second time the Golden Eagles matchup with Vanderbuilt, suffering a 6-0 loss in August. Advantage: Tennessee Tech for having seen a Vanderbilt team that has been consistent all season while the Golden Eagles had a slow start before building into an unbeaten October and November. Revenge will be on their mind and it would be easy for the Commodores to overlook Tennessee Tech after the early season drubbing. It’s hard to beat a team twice, no matter who they are, and the Golden Eagles will know more about what they’re up against this time around. With five shutouts in a row coming into this matchup, both the offense and defense have to feel more confident than August.

Virginia

The Cavaliers lost in the first round of the ACC Tournament to Stanford, but spent much of the year as no.1 in the rankings. At 12-3-4, Virginia might just be grateful for the extra rest. They’ll play High Point University in a North v South Carolina matchup. HPU won the Big South Tournament on penalties to sneak into the NCAA tournament with a 5-9-5 record.

The regional rivalry and mentality to win on penalty kicks are probably to High Point’s advantage. It was a win or end the season situation, and the Panthers won out. The Cavaliers on the other hand snuck through the first round on penalties and then were bounced by Stanford. This season, their two regular season losses were sandwiched between a run of ties, something that High Point has to think increases their odds. Coming out and frustrating Virginia for the first 15 to 30 minutes could be enough to let doubt start tensing up the Cavaliers. It’s a half chance, but that’s all High Point’s needed this far.

A No.1 seed being knocked out in the first round is improbable, but never impossible. It’s been done before and the four unseeded teams facing the no.1s know it only takes one good bounce to knock out a favorite.