10 football teams on upset alert this weekend

They're often very hard to predict but seem to happen every weekend. Upsets are one of the things that make football, especially at the high school level, so exciting.

MaxPreps looks at 10 games where the underdog could come out on top:

Lake Travis (Austin, Texas)
Opponent: Tivy (Kerrville, Texas)
Game: Friday, 7:30 p.m.
Lake Travis looked exceptional in its throttling of highly acclaimed Aledo, so much so that it jumped into the Xcellent 25. It would appear that No. 22 Lake Travis should have an easier go of it against Tivy, but don't be surprised if Tivy makes it interesting. Even without departed star Johnny Manziel, the team is playing well, winning its first two games by a combined score of 94-7 before dropping a 38-26 decision to a very good Cibolo Steele squad.
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Trinity (Louisville, Ky.)
Opponent: St. Xavier (Cincinnati)
Game: Friday, 7:30 p.m.
In most of their recent matchups, St. Xavier entered this contest as the favorite. But this season, after three incredibly dominant performances — highlighted by a 56-7 dismantling of Elder — Trinity could win big. However, playing on the road at St. Xavier is never easy, and the Bombers' defense will be one of the best that Trinity sees all season. If St. Xavier can dictate the pace of the game and keep Trinity's offense off the field, it certainly has a shot at upsetting the nation's No. 5 team.
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Piscataway (N.J.)
Opponent: South Brunswick (Monmouth Junction, N.J.)
Game: Friday, 7 p.m.
Greater Middlesex Conference power Piscataway followed up its 12-0 season in 2010 with a 47-0 thumping of Edison. With great size up front and game-breaking skill players, it has a great chance to finish undefeated. South Brunswick may play spoiler. They opened many eyes around New Jersey with a 14-7 victory over Sayreville last weekend and have athletes, like Jevon Tyree, who can run with Piscataway.
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Ensworth (Nashville, Tenn.)
Opponent: Baylor (Chattanooga, Tenn.)
Game: Friday, 7 p.m.
One on the nation's top teams on the rise, Ensworth looks like it could be the best team in the state of Tennessee. Baylor, which narrowly lost to Ensworth in last year's Division II-AA final, is also off to a hot start at 4-0 and has upset on its mind. Taking over for last year's Mr. Football Jacob Huesman, dual-threat quarterback Matthew Oellerich leads Baylor's precise offense, which will challenge Ensworth's defense.
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Long Beach Poly (Calif.)
Opponent: Narbonne (Harbor City, Calif.)
Game: Friday, 7 p.m.
After a disappointing 2010, Long Beach Poly has looked very strong early on in 2011, with victories over Grant and Carson. Narbonne, which led at halftime against Poly last year before squandering the lead, is a clear underdog but has arguably the best player on the field in quarterback Troy Williams. In Tray Boone and sophomore Johnell Jackson, Narbonne has some terrific complementary players to Williams and may give the Jackrabbits a shock on Friday.
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Skyline (Sammamish, Wash.)
Opponent: Lake Oswego (Ore.)
Game: Friday, 7 p.m.
Although Skyline is coming off a loss to Bellevue, it features star quarterback Max Browne. Not to mention, Washington teams have fared well against competition from the neighboring state to the south. While not as acclaimed as Browne, Lake Oswego quarterback Alex Matthews has been very effective for Steve Coury's squad, which would love to exact revenge for the 38-14 loss it received at Skyline's hands last season. This year, Skyline will have to travel, another factor that could tip the outcome in Lake Oswego's favor.
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Central (Miami)
Opponent: Cocoa (Fla.)
Game: Saturday, 7:30 p.m.
Cocoa is smaller, may be worn out from traveling, and is not 100 percent healthy. As such, Central should win easily, right? Maybe, but maybe not. Cocoa has surprised bigger teams before, and was competitive against Colerain and Skyline this season. Head coach John Wilkerson's squad is playing at home and is hungry for a win, so Cocoa may send shockwaves around the Sunshine State.
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St. Edward (Lakewood, Ohio)
Opponent: Elder (Cincinnati)
Game: Saturday, 7 p.m.
Entering the season nationally ranked, No. 9 St. Edward has not disappointed, grinding out three wins against solid competition. It is the definitive favorite in this game and has as good of a chance as anyone to capture Ohio's Division I crown this season. Elder struggled mightily against Trinity last week, but is still a good football team. It will be looking to bounce back. If Elder can put some points on the board early, and force St. Edward to play from behind, it may be able to hang on for an upset.
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De La Salle (Concord, Calif.)
Opponent: St. Mary's (Stockton, Calif.)
Game: Friday, 7:15 p.m.
The depth of teams in Northern California is very impressive this season. In past years, it seemed to be De La Salle, Grant and everyone else. But no longer. The Spartans barely survived an upset bid by Bellarmine in week one. St. Mary's, which beat Lincoln (Stockton, Calif.) last season, got off to a rocky start by losing its season opener but rebounded by beating Central Catholic last week. If Bowe Merin can attack De La Salle's secondary and connect with Giovanni Brusa, it will be able to score on De La Salle and make it a game.
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Centennial (Corona, Calif.)
Opponent: Mater Dei (Santa Ana, Calif.)
Game: Friday, 7:30 p.m.
Centennial lost a slugfest to St. Bonaventure in its opener last week, but definitely looked like one of the state's elite teams. Conversely, Mater Dei struggled in a 26-22 loss to Carson. Last season, Centennial won this contest easily, but this rivalry has produced some wild outcomes, most notably Mater Dei's 51-37 victory in 2007 in a game that featured 1,298 yards of offense. If junior quarterback Ryan McMahon can learn from last week's mistakes and display the consistency he demonstrated over the summer, Mater Dei has a chance.