Tamudo is Espanyol's record goalscorer with 129 goals in 340 matches between 1996 and 2010 and despite acknowledging that Los Periquitos will always have a place in his heart, he is now focused on winning games for Rayo.
"For me, playing against Espanyol isn't just another game. Last year I faced them when I was with Real Sociedad but it felt strange after spending almost my entire life there.
"Football is like this, but the truth is I never thought I would ever play against Espanyol, although now it is important to win for Rayo.
"It is two years since I left Espanyol and after such a long time I now only think about my team, about playing well and scoring goals, but I have some fantastic memories of my time there and I will always cherish them."
Tamudo has already found the net twice since joining Rayo in the summer but knows it is important for his side to get back on winning ways after a run of only one point from the last three games.
"Three points would give us a lift," he said. "We seem to have been doing pretty well so far and, although the reality is we only have six points, the team could have had more.
"It is clear that to achieve our objectives we have to be strong at home, make the most of our stadium and our fans and take the three points against Espanyol."
Alejandro Arribas suffered a back injury two weeks ago in the 1-1 draw with Racing Santander and is Rayo's only absentee through injury.
Espanyol will be looking to end a miserable run of form away from home which has seen them take only one point from a possible 33 in away games in the league stretching back to February.
Mauricio Pochettino will have Jordi Amat and Walter Pandiani back from suspension after both missed the 4-0 defeat to Real Madrid last time out. However Felippe Mattioni and Juan Albin are still unavailable through injury.