* Unemployment running at lowest levels in two decades * Jobs revival key to president's recent reelection BUENOS AIRES, Nov 21 (Reuters) - Argentine unemployment dipped to 7.2 percent in the third quarter from 7.5 percent in the same period a year earlier, the state statistics agency said on Monday. The official jobless rate matched the figure announced in October by President Cristina Fernandez, a center-leftist who won easy reelection for a second four-year term last month. Argentine unemployment is at its lowest in two decades thanks to years of strong economic growth but political analysts say keeping people in jobs will be a leading challenge for Fernandez as the global economic outlook worsens.Argentina, Latin America's No. 3 economy, is growing at one of the region's fastest rates fueled by government-stimulated consumer demand, grains exports and industrial output. Unemployment was 7.3 percent in the second quarter of 2011.