Phasor Measurement Units (PMUs) are increasingly being deployed to augment monitoring, protection and control applications in the power grid. PMUs rely on the Global Positioning System (GPS) for generation of time-synchronized and accurate measurements. However, civilian GPS signals, being unencrypted, are susceptible to GPS spoofing attacks (GSA). Hence ensuring the integrity of GPS-timing dependent synchrophasor data has become critical. In this paper, a closed-form analytical solution for estimating the GSA phase shift has been proposed and integrated to the spoofing detection & correction framework. Extensive simulations have been performed in order to verify the accuracy of the solution in determining the location and the phase shift of the compromised PMU. Time domain dynamic simulations presented in this paper demonstrate the applicability of the proposed solution for near-real-time detection of GSA, and this will enable faster detection and correction of phase angles of compromised synchrophasor data.