Hepatitis C virus (HCV) RNA decay during antiviral therapy is characterized by a rapid first phase followed by a slower second phase. The current understanding of viral kinetics attributes the magnitude of the first phase decay to the treatment effectiveness, whereas the second phase decay is attributed to the progressive loss of infected cells. Here we analyzed data from 44 patients treated with telaprevir, a potent HCV protease inhibitor. Using a viral kinetic model that accounts for the pharmacokinetics of telaprevir, we found that the second phase slope of viral decline to be strongly correlated with the treatment effectiveness and to be roughly four-fold more rapid than has been reported with interferon-based therapies. Since telaprevir is not known to increase the death rate of infected cells, our results suggest the second phase slope of viral decline is driven not only by the death of infected cells but may also involve other mechanisms, such as a treatment effectiveness-dependent degradation of intracellular viral RNA. As a consequence of the enhanced viral decay caused by the high antiviral effectiveness of telaprevir, we predict that if drug resistance could be avoided by using an appropriate combination of antiviral agents, treatment duration needed to clear HCV might be dramatically shortened. Indeed, we predict that in 95% of fully compliant patients, the last virus particle should be eliminated by week 7 of therapy. If the remaining infected hepatocytes act as a potential reservoir for the renewal of infection, no more than 10 weeks of treatment should be sufficient to clear the infection in 95% of fully compliant patients. However, if patients miss doses, treatment duration would need to be extended.