The goalkeeper saved his side in the last minute of regular time, and denied Ayala from the spot to send Universidad into the semi-finals
Holding a slim advantage at the outset thanks to the away goal scored in Asuncion, Universidad de Chile nevertheless started Thursday's clash with their customary intensity and hectic attacking play. A deep cross into the box found Angelo Henriquez with space, but the striker could only head over the bar to miss out on the chance to drive the Santiago side into the lead.
Libertad also threatened early on, mainly due to excellent work down the left flank by Luciano Civelli. The ex-Ipswich Town player put a tantalising cross into the box after exploiting gaps in the U defence, but Albert Acevedo was on hand to clear the danger and deny the waiting Pablo Velazquez. And with just over a quarter of an hour played, Universidad de Chile, fired themselves into a 2-1 lead overall.
Gustavo Lorenzetti bamboozled the Libertad midfield before releasing Henriquez, who appeared to be away before Cristian Nasuti cynically cut his path short to earn himself a yellow card. It mattered little though; from the resulting free kick, Marcelo Diaz cleverly fired his effort underneath the wall and into the bottom right corner to put his side one up.
The Repolleros did not lose faith, and almost instantly hit back. Victor Ayala launched a free kick deep into the Azul area, and Oswaldo Gonzalez got the final tough to send the ball past his own keeper for the equaliser. The goal shook Jorge Sampaoli's men, and Jorge Nunez had a golden chance to put the Paraguayans ahead when he broke the offside trap - only to be denied by the imposing Jonny Herrera in goal.
Eugenio Mena thought that he had restored the lead for the hosts shortly after half time after a clinical break, but the midfielder was clearly offside when he received the ball and his effort was disallowed. Universidad rediscovered some of the pace and purpose that deserted them in the first period, but found attacking hardgoing against the stout defence of the visitors. The half yielded few decent chances for either team, although Rodriguez forced Rodrigo Munoz to be at attention in goal with a well-hit half-volley.
Diaz thought for a second that he had repeated his free-kick heroics, when his lofted effort spiralled towards goal. Munoz denied the U player, however, palming the ball onto the bar to keep scores level and the spectre of penalties on the horizon. Minute later the goalkeeper again came to Libertad's rescue, as he dived at full stretch to block Rodriguez's deflected shot.
The Repolleros finished the match on the back foot, although a last-minute header from Velazquez was brilliantly saved Herrera; but the Paraguayans held on to send the match to the second penalty shootout of the evening.
After five successful kicks Ayala was the first to miss, his effort saved by the heroic Herrera to put the U 3-2 up. Matias Rodriguez buried his attempt, and another success from Libertad keeper Munoz meant it was down to Lorenzetti to win the game. He sent Munoz the wrong way to finish, and confirm Universidad's agonising victory.
The U will move on to play Boca Juniors in the Copa Libertadores semi-final, the pair fighting for the right to meet one of Santos or Corinthians in the final.