Sevilla made an ideal start as Carlos Bacca opened the scoring after just two minutes and things twent from bad to worse for the visitors - who remain bottom and without a win in seven La Liga matches.
Paulao was shown two yellow cards in the space of five minutes before Stephane Mbia headed home from a free-kick.
Vitolo made it three a minute short of the hour-mark and Vicente Iborra rounded off the scoring after 88 minutes as Sevilla beat Betis by four goals at home in the derby for a second successive season, having triumphed 5-1 in the corresponding fixture last season.
Elche recorded a surprise 2-1 win against Valencia, with Fidel putting the home side ahead after 57 minutes only for substitute Juan Bernat to equalise just two minutes after coming on.
It was another substitute who stole the headlines however, with Cristian Herrera scoring the winner on his senior debut six minutes from time.
The win puts Elche level on points with Valencia and Fran Escriba's men are now above them on goal difference.
Villareal strengthened their grip on fourth place with a convincing 3-0 victory over Levante on Sunday.
Levante, who have now scored just once in their last four games, suffered their third straight defeat as they were well beaten on home turf.
Bruno Soriano opened the scoring for the visitors from the penalty spot 13 minutes in, with Keilor Navas shown a red card for the foul that resulted in the spot-kick.
From then on it was always going to be a tough ask and the hosts held out until the 74th-minute, when Ikechukwu Uche fired home from inside the area to score for a third straight game and he added another goal late on.
A Sergio Garcia hat-trick condemnded Rayo Vallecano to a fourth defeat in five La Liga matches, with the visitors going ahead from the spot at the Estadio del Rayo Vallecano after Ignacio Martinez was sent off 25 minutes in.
Garcia added another penalty six minutes after the break before Saul Niguez pulled one back nine minutes from time.
However, Garcia and Cristhian Stuani struck in the final seven minutes to seal a comfortbable victory.
