Villarreal only took one point from their last three league games before the winter break and currently sit sixth in the overall standings.
Asenjo, who is on loan at the club from Atletico Madrid, knows it is time to step up to the mark against a struggling Rayo side who resume second bottom of the league on Monday and two points adrift of safety.
"It's time to react and use our weapons to get the three points needed," Asenjo told Marca.
"We have faced this week off to recharge our batteries and free the mind.
"We must go back to the winning ways with which we started the season."
Villarreal's last league win was against Levante on November 24, while Rayo tasted success against Real Valladolid in the fourth round of the Copa Del Rey but are winless in La Liga since a 2-0 win over Celta Vigo almost two months ago.
Rayo returned to training after the break without midfielder Jonathan Viera and defender Ze Castro due to illness, with Johan Mojica sitting out as a precaution.
The home side could lose out in the race to sign striker Leo Baptistao, according to reports in Spain, with the Atletico Madrid forward seemingly poised to sign for Real Betis, although West Ham are also believed to be interested in the 21-year-old.
Rayo manager Paco Jemez said: "If Leo is going to Betis, I wish the best for him and for Betis in this new phase."