Introduction: The present study aimed to explore how athletes respond to different behaviors of their opponents. Methods: Twelve moderately to highly physically active participants with at least two years of cycling experience completed four 4-km time trials on a Velotron cycle ergometer. After a familiarization time trial (FAM), participants performed three experimental time trials in randomized order with no opponent (NO), a virtual opponent who started slower and finished faster compared to FAM (OP-SLOWFAST), or a virtual opponent who started faster and finished slower compared to FAM (OP-FASTSLOW). Repeated-measures ANOVAs (P < 0.05) were used to examine differences in pacing and performance related to power output, velocity and RPE. Results: OP-SLOWFAST and OP-FASTSLOW were completed faster compared to NO (385.5 ± 27.5, 385.0 ± 28.6, and 390.6 ± 29.3 s, respectively). An interaction effect for condition × distance (F = 3.944, P < 0.001) indicated differences in pacing profiles between conditions. Post-hoc analysis revealed that a less aggressive starting strategy was adopted in NO compared to OP-FASTSLOW and OP-SLOWFAST during the initial 1000 m. Finally, a faster starting opponent evokes higher power outputs by the participants in the initial 750 m compared to a slower starting opponent. Conclusion: The present study is the first to show that the behavior of an opponent affects pacing-related decisions in laboratory-controlled conditions. Our findings support the recently proposed interdependence of perception and action, and emphasize the interaction with the environment as an important determinant for an athlete's pacing decisions, especially during the initial stages of a race.