This paper uses 90nm transistor-level experimental data, device modeling, and circuit simulations to establish the following results: 1. A transistor with defective gateoxide,i.e., a gate-oxide early-life failure (ELF) candidate transistor, produces gradually degraded drive currents over time before it completely loses its transistor characteristics; 2. The above phenomenon results ingradual increase in delays of digital circuit paths containing the ELF candidate transistor before the circuit produces functional failures; 3. Gradual delay shifts caused by ELF candidate transistors are large enough to be detected using inexpensive digital techniques. These results can be utilized to overcome scaled-CMOS reliability challenges through ELF identification during production test or on-line during system operation.