Male (Fontinella pyramitela Linyphiidae) engage in dangerous fights over access to females. Males assess relative fighting ability during contests: smaller individuals tend to give up quickly. Fights occur between a male with information about the value of the contested female (number of fertilizable eggs) and an intruding male with less information. A sequential assessment game (a game theory model of fighting behavior) is adapted to male combat to attempt a quantitative test. The model makes predictions about fight duration, probability of winning, and the occurrence of fatalities as a function of resource value and size asymmetry. -from Authors