A Head-to-head wager is a variety of sports betting whereby the bookmaker creates a market for the two possible outcomes of a match:
Team A win or Team B win.
Sometimes, head-to-head bets involve three outcomes; an example of a sport where three outcomes is a recognizable possibility is soccer, where the draw can be as likely as any other result.
Real Madrid +104
FC Barcelona -136
In NASCAR and professional Golf, a common way to wager on these events is to do it on the head-to-head results between just two competitors. Whichever one finishes the race or the tournament in the higher position wins. Many times a moneyline will be attached to each competitor to handicap the match.
This type of bet is very popular, because of the greater difficulty that involves picking an outright winner among an especially large pool of opponents.
Similarly, Horse Matchup betting is a wager between two horses that instead of handicapping an entire field, it comes down to the handicapper deciding between two horses. Comparable to a moneyline on a sporting event, there is usually a favorite and an underdog.