Miguel “Michu” Perez and Raul Tamudo put Rayo in command, before Julien Escude pulled one back for Sevilla.
“Taking into account that [Reyes] was playing with new teammates and that he hadn’t played much recently, he played well,” Sevilla coach Marcelino Garcia said of the former Arsenal player, who returned to his boyhood club from Atletico Madrid on Thursday.
Elsewhere, Valencia came from two goals down to draw 2-2 at Villarreal in coach Jose Molina’s debut for el Submarino Amarillo. Athletic Bilbao drew 0-0 at Getafe and Real Betis Balompie beat nine-man Sporting de Gijon 2-0 for a third straight win.
Villarreal remain winless in nine consecutive games in all competitions, while Valencia stay in third place, nine points behind league leaders Real Madrid.
Athletic Bilbao striker Fernando Llorente returned after missing seven games with a left-knee injury and teammate Iker Muniain set the record for the youngest player to have made 100 La Liga appearances at the age of 19 years, 20 days.