Paraguayan side Olimpia put themselves on the brink of the Copa Libertadores final with a 2-0 win over Santa Fe of Colombia in the first leg of their last-four clash.
Herminio Miranda netted the opener in the 65th minute with a penalty and Juan-Carlos Ferreyra doubled the lead 10 minutes from time, while both sides played the second half with 10 men after Brazilian referee Heber Lopes sent off Olimpia striker Juan-Manuel Salgueiro and former Colombia midfielder Gerardo Bedoya for a clash in first-half stoppage time.
Olimpia coach Ever Hugo Almeida felt his side would miss the attacking power of Salgueiro so brought on Ferreyra at half-time.
However, the crucial substitution by Almeida was bringing Alejandro Silva on for Ricardo Mazacotte, as Silva's running and accuracy gave Olimpia more power from the first minute of the second half, pushing the Paraguayan giants forward to clinch the advantage ahead of the second leg in Bogota next week.
Silva came off the bench alongside Salgueiro and was very dangerous in the opening minutes of the second period, with a 55th-minute strike from outside the box saved by Santa Fe keeper Camilo Vargas.
Julio Manzur had a good opportunity but his header, after a Silva free-kick, went narrowly wide of the right post in the 61st minute.
The crucial moment came three minutes later when Silva was brought down by Vargas in the box and Miranda opened the scoring from the spot.
Olimpia went for a second, backed by 32,000 supporters at the Estadio Defensores del Chaco, and Santa Fe were shellshocked.
With 10 minutes to go, Eduardo Aranda started a counter-attack, passing the ball to Silva, who assisted Ferreyra. The striker had a simple finish to make it 2-0.
Ferreyra, who was not fully fit, was replaced soon after by Enzo Prono, who could have made it 3-0 in the 86th minute, but Vargas saved his shot with his foot, then stopped a Matias Gimenez attempt in stoppage time to keep his side in the tie.
Silva told Fox Sports: "The 2-0 scoreline is very, very important, but we must not be excessively confident. We have to play in Colombia yet, but we have a little advantage.
"It was not an easy game at all. Santa Fe had the ball a long time and marking them was difficult."
Ferreyra added on his physical problems: "I had a tear during a league game and tonight I felt some pain. I think I will be fine for the return match.
"What matters is that my goal helped us win. We are very happy but we have not achieved anything yet."
The other semi-final sees Newell's Old Boys of Argentina meet Brazil's Atletico Mineiro.
Information from the Press Association was used in this report.