This paper aims to analyze the discontinuous crack closure behavior observed after a single tensile overload (OL) under otherwise constant ΔK loading. The investigation was performed on a disk-shaped compact tension DC(T) specimen made of Al6351-T6 with thickness of 2 mm, in order to simulate the case of a crack propagating under plane stress conditions. The Digital Image Correlation (DIC) technique was used in situ to obtain the full-field displacement and strain solution around the crack surfaces during the fatigue crack propagation. The experimental data obtained from DIC analysis revels that the residual hump of stretched material left in the wake of the propagating crack by the overload acts like a compliant spring, leading to a discontinuous crack closure mechanism. Moreover, this residual hump has a significant effect on the post-overload transient crack growth, even at distances much larger than the plastically deformed area created by the overload in front of the crack tip.