Five-times golf major champion Seve Ballesteros, recovering from surgery on a life-threatening brain tumour, urged his local team to believe they can score the goals that would send them through in their last-four second leg in Santander.
"Boys! Five goals are what we need," Ballesteros said in a message posted on his website, adding that he would try to attend the match at the Sardinero stadium.
"Impossible is a word I have never liked," he said. "We have 90 minutes to achieve something that is difficult, but, I insist, not impossible. Let's go Racing! Good luck Racing!"
After Atletico cruised to a 4-0 win in Madrid in last week's first leg, the two sides met in Santander in La Liga on Sunday, with the home side battling back from a goal down to earn a 1-1 draw.
Racing coach Miguel Angel Portugal praised his players for picking themselves up from their Cup thrashing.
"The reaction of the team after the defeat in the Cup was extraordinary," he told a news conference.
"Racing were in charge of the game from start to finish. "With one more goal we would have put the fear of God into the Atletico players (for the Cup return leg)."
SUPRISE DEFEAT
The winners of Thursday's tie will face 2007 winners Sevilla or the team the Andalusians beat in the final that year, Getafe, in May's final.
Sevilla have a two-goal cushion for Wednesday's second leg in Madrid but suffered a surprise 2-1 defeat at promoted Real Zaragoza in La Liga on Sunday.
They finished the match with nine men after the referee sent off Alvaro Negredo and Marius Stankevicius, and coach Manolo Jimenez said he was concerned about the team's vulnerability in dead-ball situations.
"It was a match to forget in every aspect, from start to finish," he said at a news conference.
"What I do guarantee is that the 11 players who take to the pitch in Getafe will be competitive and the match will be a completely different story."
Getafe lost 2-1 at La Liga leaders Barcelona on Saturday.
