Uruguay dumped Argentina out of the Copa America in Santa Fe, with Carlos Tevez's penalty miss proving crucial in the quarter-final shootout.
Gonzalo Higuain's equaliser had got Sergio Batista's side level in the 17th minute, cancelling out Diego Perez's early opener, and things looked to have turned in the hosts' favour when Perez was sent off six minutes before the break.
But Javier Mascherano's red card three minutes from time evened up the numbers and, when there were no further goals after extra time, Uruguay goalkeeper Fernando Muslera took centre stage. He made the only save of the shootout from Tevez's spot-kick.
The Charruas will face Peru, who earlier beat Colombia 2-0 after extra time, in the first semi-final on Tuesday.
Oscar Tabarez's side stunned the home crowd by taking a fifth-minute lead at the Estadio Brigadier Estanislao Lopez.
Argentina goalkeeper Sergio Romero made a good diving save to keep out Martin Caceres' header from Diego Forlan's free-kick, but Perez pounced to squeeze home the opening goal.
Their lead lasted only 12 minutes, though, before Real Madrid forward striker Higuain glanced home a fine cross from Barcelona's Lionel Messi.
Uruguay suffered a further blow before the interval when midfielder Perez was given his marching orders for a second bookable offence following a foul on Fernando Gago.
Despite their numerical advantage, Argentina looked shaky at the back and the lively Luis Suarez threatened to put Uruguay ahead again but to no avail, while Messi, Higuain and Sergio Aguero were also unsuccessful in their quest to find a way past Muslera.
Mascherano saw red for a second bookable offence after fouling Suarez towards the end of normal time, leaving it 10 men apiece for the additional 30 minutes.
Javier Pastore and Tevez were introduced in place of Angel Di Maria and Aguero and caused a few problems for Muslera and the Uruguay defence, but neither could grab the crucial goal.
Higuain passed up a glorious chance to win it for Argentina, smashing his shot against the post with only Muslera to beat.
And man-of-the-match Muslera was to prove the key figure in the shootout, keeping out Tevez's third spot-kick for Argentina.
Messi, Nicolas Burdisso, Pastore and Higuain were all successful for Argentina while Forlan, Suarez, Andres Scotti, Walter Gargano and Caceres kept their cool for Uruguay.
Muslera was thrilled to have helped his side advance to the last four.
"We are very, very happy to make such a big step in the tournament," said the 25-year-old Lazio goalkeeper.
"I hope I have just played one of the best matches in my short career. I'm very happy for all the people in Uruguay. This team deserves this win.
"We were better than Argentina, even playing with 10 men. Then, penalties are just a matter of luck."
Defender Diego Lugano added: "We fought more than we played.
"There is a long way to go yet. We have not achieved anything, but we defeated the most difficult rival."
