Ruben Castro scored one goal and set up another as Real Betis beat Rayo Vallecano at the Vallecas Stadium for the first time since 1999.Heiko Westermann exchanged passes with Castro and opened the scoring in the 20th minute and the Spanish striker extended the lead just after the hour mark.Vincenzo Rennella had gone close for Pepe Mel's men before they went in front when German defender Westermann worked a one-two with Castro and netted his first goal since joining the club from Hamburg in the summer.Castro could have doubled Betis' advantage before half-time but he was off target with his effort.However, he did get his name on the score sheet in the 61st minute. Alvaro Cejudo punished defender Ze Castro's mistake and presented Castro with a one-on-one, with the striker slotting home for his fourth goal of the season.The hosts offered very little as an attacking force and were making mistakes at the back.Substitute Joaquin almost added a third for Betis with 12 minutes remaining but his shot struck a post.Betis had been beaten on each of their last four visits to Rayo but comfortably saw out the game to record back-to-back away victories in the Primera Division.