One example of a sports metaphor is the use of the phrase "down to the wire" to describe non-sports situations in which time is running short. The metaphor derives from horse racing, in which a wire marks the end of the track.
A related metaphor is the use of "under the wire", to indicate that something occurred at the last moment. Using the phrase "below the belt" to describe bad or tricky behavior is a metaphor that derives from boxing, where hitting below the belt is against the rules. "Throwing in the towel" is a common metaphor for giving up that also stems from boxing.