Hosts Chile reached their first Copa America final in 28 years after seeing off the 10 men of Peru in a thrilling encounter in Santiago.
Chile could have had midfielder Arturo Vidal sent off early on before Peru defender Carlos Zambrano was dismissed.
Former QPR striker Eduardo Vargas then put Chile ahead after Alexis Sanchez had hit the post but Peru levelled through a Gary Medel own goal.
But Chile deservedly won it when Vargas fired home a fine second from 25 yards.
Chile have never won the Copa in 99 years of trying but will now play either Argentina or Paraguay in Saturday's final.
Juventus midfielder Vidal was lucky to escape punishment for thrusting his hand into the face of marker Zambrano before Peru hit the post through Jefferson Farfan's header.
Zambrano was not shown the same leniency from referee Jose Argote in the 20th minute when he was shown a straight red card after catching Charles Aranguiz on his follow-through as he cleared the ball downfield.
Peru were furious and were further aggrieved before half-time when Sanchez's cross struck the post and Vargas scrambled in, with replays suggesting the striker was marginally offside.
The two contentious decisions were the latest chapters in a tournament marred by controversy on and off the pitch.
Brazil superstar Neymar was suspended for four matches after being sent off and then clashing with players against Colombia; Chile midfielder Vidal was banned from driving but cleared to play on after a car crash while allegedly drunk; and his team-mate Gonzalo Jara is serving a ban after an incident in which he appeared to poke his finger against Uruguay striker Edinson Cavani's backside.
After the break Vargas was this time unlucky to see a strike incorrectly ruled out offside before Peru counter-attacked to perfection to level.
Former Cardiff midfielder Medel stretched to cut out an excellent cross from right-back Luis Advincula but could only turn past his own goalkeeper Claudio Bravo.
Peru had deserved their equaliser but were behind again four minutes later when the busy Vargas lashed in a stunning second, dipping a shot beyond Pedro Gallese from 25 yards.
Peru, who also lost in the 2011 semi-final, tired after that goal and Arsenal forward Sanchez clipped the top of the bar from an angle as Chile saw out the win.