Sabotage describes deliberate actions that weaken an opponent. The methods of sabotage include, but are not limited to destruction of property and disruption of the work flow.
Sabotage has a humorous origin: "sabots" were wooden shoes that the working class in Europe wore in the 1600s and afterward. Once the industrial revolution began in the 1700s, workers would throw their "sabots" into any machinery that was malfunctioning in order to derail or stop it.
The basic premise of tournament theory is that the participant with the "best result" (only compared to the other participants, not by some sort of absolute criterion) will get a major reward.
To achieve this aim (become better than all participants), a participant may either increase his own performance or sabotage the others in order to look better without actually having improved.
As with the rat race problem, possible countermeasures are decreasing the reward (in order to discourage such behavior) and separating the participants (to decrease the information needed to determine when to use sabotage).