Roberto Soldado and Juanma Mata scored two goals apiece to lead Valencia to a 5-0 rout of Villarreal, strengthening their hold on third place in the Spanish league.
Soldado scored Valencia's first-half opener at Mestalla stadium, while Mata scored two, Ever Banega added another and Soldado capped the demolition of their provincial rivals in the second half.
"We knew that we could lose this game, but not in this way and not by such an excessive result," Villarreal coach Juan Carlos Garrido said.
Valencia's second straight win lifted them six points clear of Villarreal in their bid for the last automatic Champions League qualifying spot.
Elsewhere, Atletico Madrid moved into sixth place with a 3-0 win over Real Sociedad.
Valencia controlled the first half and went ahead when Villarreal lost possession and right back Miguel Garcia played Soldado through for the ex-Getafe striker to slot the ball under goalkeeper Diego Lopez in the 14th minute.
Villarreal was fortunate to reach half time only a goal down, as Valencia failed to take a series of chances. Mata made it 2-0 after working a one-two with Banega before rifling past Cesar Lopez in the 56th minute. "The second goal took away our hopes of a comeback," Garrido said.
Villarreal wilted, and Pablo Hernandez raced past a defender before his cutback found Lopez for Valencia's third goal in the 62nd.
Hernandez then beat the offside trap and laid the ball off for Mata to score in the 73rd, and two minutes later Soldado chipped Lopez after Villarreal lost the ball on the edge of their area to complete the demolition. Soldado has six goals in the last two games and 12 this season.
Atletico put on one of its most dominating performances of the season at Vicente Calderon stadium, creating enough chances to thrash the struggling Sociedad before half time.
Atletico coach Quique Sanchez Flores left striker Diego Forlan on the bench for the second straight week in favor of Diego Costa in attack alongside Sergio Aguero, who was back from a one-game suspension.
"It was a complicated decision (to not start Forlan) because we value him highly," Sanchez Flores said. "He shouldn't be down and just needs to keep working like he has until now."
Aguero forced a diving save from goalkeeper Claudio Bravo before Costa set up Filipe Luis with a backheeled pass for the Brazilian left back to fire into the roof of the net in the 12th minute.
Atletico pushed the visitors back into their area, and the pressure paid off when Jose Antonio Reyes made Sociedad defender Carlos Martinez fall to the ground with an incredible feint before drawing Bravo to him and laying off for Mario Suarez to tap home in the 45th.
Aguero sealed his team's second straight win to score from a counterattack in the 78th for his 13th goal of the season.
The Argentina forward's goal was a superb individual effort, sprinting past two defenders before beating Bravo with a shot into the left corner of the net.
Forlan, who had come on for Costa, almost hit Atletico's fourth when he flashed a free kick past the post and then sent a shot over the top.
"Atletico is playing well, it's on the rise, and we didn't know how to stop them," said coach Martin Lasarte, whose Sociedad is now five points above the drop zone after their fifth consecutive loss.
Earlier, substitute Rafa Jorda equalised in the 90th minute to give Levante a 1-1 draw at Racing Santander after Victoriano Rivas' own goal in the 32nd. "It would have been unfair for us to lose this game," said coach Luis Garcia, whose Levante has not lost in seven weeks.
David Barral's 66th-minute goal earned Sporting Gijon a 1-0 win over Osasuna as Manolo Preciado's team remained undefeated in the last seven games at El Molinon stadium.
Ten-man Deportivo held on to draw 0-0 at Malaga after Laureano Sanabria was dismissed on the stroke of half time, and Espanyol drew 0-0 at Hercules.