Abstract: We discuss a two-species Lotka-Volterra competition-diffusion model with a shifting habitat. The growth rate of each species is nondecreasing along the x-axis, and it changes sign and shifts rightward at a speed c. We investigate the population dynamics of the model in the habitat suitable for growth of both species for two cases: (i) one species is competitively stronger and has a slower spreading speed, and (ii) both species coexist. We obtain conditions under which the outcome of competition depends critically on a number c1 given by the model parameters. We show that under appropriate conditions, if c1> c then the species with the faster spreading speed spreads into the open space at its own speed and the species with the slower spreading speed spreads into its rival at speed c1, and if c1< c then the species with the slower spreading speed eventually dies out in space. Our results particularly demonstrate the possibility that a competitively weaker species with a faster spreading speed can drive a competitively stronger species with a slower spreading speed to extinction. The mathematical proofs involve linear determinacy analysis, integral equations, and comparison.