The La Liga surprise package stunned neighbours Atletico with a 2-1 victory last weekend and Piti is confident they can follow that up with another derby triumph over Real - despite the fact their star-studded opponents have not lost at home in La Liga since 2011.
Piti said: "With our play and the desire that we have, we will try to get the three points. I would put an 'away win' on the betting coupon, I have a lot of confidence in myself and my team and I know we can do it, we are in good form.
"We're really looking forward to facing Real Madrid, all footballers like these games against an opponent who maybe aren't going through their best moment but are still very good."
Rayo's win over second-placed Atletico left them sixth in La Liga on 37 points, two adrift of Malaga who occupy the fourth and final Champions League berth.
The club's impressive showing this season is in stark contrast to last term when they only survived an immediate return to the Segunda Division by winning on the final day.
Midfielder Jose Manuel Casado said: "Everybody is talking this season about Rayo having to stay up but I don't see it like that. I think we are close to being safe.
"At the start of the season that was our only objective, but the team has shown that up to this point we are better than a lot of teams.
"If we continue with the same ambition, we can achieve something very good."
While Rayo have largely been punching above their weight, Madrid have struggled in the defence of their La Liga title.
They bounced back from their shock defeat to Granada a fortnight ago with a 4-1 home mauling of Sevilla last weekend, but while that lifted them to within four points of Atletico they remain a massive 16 points adrift of pacesetters Barcelona .
Mourinho's men were unable to follow that up with a victory in midweek as they were held to a 1-1 draw by Manchester United in the first leg of their Champions League last 16 tie at the Bernabeu.
That result came after Madrid also drew 1-1 at home with Barca in the first leg of their Copa del Rey semi-final, leaving the capital club facing an uphill fight to progress in either competition.
Despite that, Mourinho is remaining calm, saying after the United match: "I feel no pressure. I work hard and I'm going home content with what I have done and with my head held high. Sometimes you win and others lose.
"The two results in the Champions League and the cup are 1-1 draws, with the opponent having the advantage, but Real Madrid can score goals and win matches away".
Sunday will see Mourinho take charge of his 100th league match with Madrid, something he has only done with Chelsea (120) previously in his coaching career.