It was the away side that started the better and they took the lead after just five minutes when Alejandro Dominguez converted from close range.
The first-half scoring was not finished there, however, and Oscar added the home side's third after 21 minutes. They continued to dominate possession as the half developed and ten minutes before the break it was four when Antonio Rukavina struck from close range.
Valladolid continued to impress early in the second period and they made it five after 56 minutes when Oscar grabbed his second of the afternoon.
Rayo continued to struggle for chances as the match approached its latter stages, with their poor run of form in La Liga showing no sign of improving as Manucho grabbed his second to make it 6-1 late on.