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If the oddsmakers in Las Vegas have it right - and they usually do (hey, those casinos weren't built on the backs of winning gamblers!) - Saturday's bout in Sin City between undefeated Floyd Mayweather and MMA superstar Connor McGregor is a very one-sided match-up favoring Mayweather. With a 49-0 lifetime professional boxing record, Mayweather is installed at -550 whereas McGregor's odds are being listed at +400.
If that doesn't make sense to you, we'll break it down a bit more simply:
If you were to lay down $100 on the Irishman and he pulled off the upset, you would win $400! If Mayweather, as the "sharps" are predicting, prevails your $100 wager would net you a whopping $18.18 profit.

If you are not the gambling type but still are rooting for the underdog nonetheless, Connor McGregor could put his name on this list of the biggest upsets in sports history compiled by

Notable Upsets In Sports History
Sept. 11, 2015: Roberta Vinci stunned Serena Williams in the semifinals of the US Open as a 12-to-1 underdog. The victory snapped Serena's 33-match Grand Slam win streak and ended her quest at the Calendar Slam.
Nov. 14, 2015: Holly Holm handed Ronda Rousey the first loss of her career at UFC 193, knocking her out by head kick in the 2nd round to win the women's bantamweight belt. Holm was an 8-to-1 underdog in the fight, making this the biggest upset in UFC history.
Feb. 3, 2008: The Patriots entered the Super Bowl 18-0 and were 12-point favorites against the Giants. The Giants at the time had the most loses of any Wild Card team that made it to the Super Bowl and lost to the Patriots in week 17.
Sept. 1, 2007: 5th ranked Michigan Wolverines fell in their season opener 34-32 to Appalachian State, a team that entered the game as a 27-point underdog.
May 3, 2007: The Dallas Mavericks entered the playoffs as the number one seed and had won 25 more games than the Golden State Warriors in the regular season. But the Warriors defeated the top-seed Mavs in 6 games. It was only the third time in NBA history that a No. 8 seed defeated a No. 1 seed.
October 20, 2004: In 2004 against the Yankees, the Red Sox became the first MLB team to win a series after being down 0-3. Boston won game 4 in extras on a walk-off home run by David Ortiz after being down 4-3 in the ninth-inning.
Sept. 27, 2000: Olympic Wrestler Alexander Karelin had never lost in 15 years of international competition before Rulon Gardner stunned him.
March 14, 1998: 16-seed Harvard beats 1-seed Stanford in the NCAA women’s tournament. Only 16 over a 1 in college basketball tournament history.
Nov. 6, 1993: Trainer Jerry Bailey guided the longshot (133-1) Arcangues to a two-length victory in the Breeders Cup Classic
April 3, 1983: N.C State’s Jim Valvano and company shocked Houston in the men’s college basketball title game with a buzzer beater.
Dec. 23, 1982: The Chaminade Silverswords, an NAIA school with 800 students at the time, beat Ralph Sampson and No. 1 Virginia.
Feb. 22, 1980: The “Do You Believe in Miracles?” Game as USA beat the Soviets – winners of the previous four gold medals.
Jan. 12, 1969: Joe Namath’s guarantee that the Jets would beat the heavily-favored Colts came to fruition in Super Bowl III. The Baltimore Colts were 18-point favorites to win.
June 19, 1955: Jack Fleck was down 9 strokes after Day 1, but came back against legendary Ben Hogan to win 1955 US Open in a playoff.
June 29, 1950: in one of the great upsets in sports history, the lightly-regarded United States beats World Cup favorite England 1-0 in the group stage of the 1950 World Cup. The US were 500-1 underdogs to beat England, and England was 3-1 to win the World Cup. Joe Gaetjens scored the only goal about 10 minutes before halftime.