Nevin let his fists go in the early exchanges. He looked to have the measure of his opponent with some nimble footwork and powerful shots.
Valdez opened up more in the second but was still being frustrated by the elusive Irishman. Valdez then walked onto two fierce right hands as he tried to work on the inside.
The Mexican stormed forward in the final round as he tried to cut the deficit, but was caught with as much as he landed. However, a heavy body shot from Valdez had him floored.
That triggered a furious assault from Valdez and Nevin was hanging on. The Irishman came under immense pressure as the seconds ticked away but he hung on to claim a 19-13 victory.