Second-half strikes from Herminio Miranda and Juan-Carlos Ferreyra earned Paraguayan giants Olimpia a healthy-looking lead to take to Colombia for this week's second leg, but Medina is convinced Santa Fe can turn things round in Bogota.
"We are full of confidence that we'll overturn the result. We have the ability and conditions to achieve that," he told Fox Sports.
If they are to eliminate three-time Copa Libertadores champions Olimpia then Santa Fe will have to do a lot better in attack than they managed in the first leg.
The Colombian outfit scored five times in seeing off Real Garcilaso in the quarter-finals but, despite enjoying plenty of possession, could not make any impression against the Olimpia backline in Asuncion.
Santa Fe's Argentinian playmaker Omar Perez hopes it will be a different story at their Estadio El Campin home, which is 2,600 metres above sea level.
He said: "Us attackers, the ones who must be offensive on the field, did not play well.
"The mentality will change in Bogota. Last week we did not have any opportunity to score and that is a very important factor to improve."
Both teams will be missing players through suspension for the second leg after Santa Fe's former Colombia midfielder Gerardo Bedoya and Olimpia striker Juan-Manuel Salgueiro were sent off following a clash in first-half stoppage time of last week's encounter.
Santa Fe coach Wilson Gutierrez has not given any clues as to who might replace Bedoya but his Olimpia counterpart Ever Hugo Almeida looks set to replace Salgueiro with Alejandro Silva as his only likely change.
Silva made a huge impact in the first leg after appearing as a half-time replacement, winning the penalty for Miranda's opening goal and then setting up Ferreyra for Olimpia's second.
That has left Olimpia in a strong position but defender Nelson Benitez know it will not be easy in the high altitude of Bogota and insists his side cannot afford to just sit back and look to keep Santa Fe at bay.
He told Cronica newspaper: "We have to play the same way as we did at home - being defensively strong, pressuring them and trying to go for the win.
"We'll not defend excessively. It's going to be hard, but we'll try to do a good job and score goals."
The Argentinian added: "We've already taken a very important step and now we must maintain our lead in Colombia.
"It's going to be tough, a difficult field, high altitude. Santa Fe will try to score the first goal as quickly as possible so we must be clever enough to find the gaps to score ourselves."
The other semi-final tie will be decided on Wednesday, when Atletico Mineiro of Brazil take on Argentinian outfit Newell's Old Boys, who also boast a 2-0 lead from last week's first leg at home.