Goals from Guillermo and Omar Ramos ensured Segunda Division Leganes will take a 2-1 lead into the second leg of their Copa del Rey last-32 tie with Granada.
The hosts took an early lead at Estadio Municipal de Butarque when Guillermo stole possession in the area and hammered home.
Things went from bad to worse for Granada midway through the opening half as Ruben Perez was sent off.
Leganes were suddenly rampant and grabbed a second seven minutes before half-time as Ramos' long-range strike made it 2-0.
However, the Liga outfit regrouped after the interval and pulled a potentially crucial goal back when Fran Rico converted in the 74th minute.