Real Madrid's Cristiano Ronaldo celebrates after scoring a penalty against Barcelona during their Spanish King's Cup semifinal second round soccer match at Camp Nou stadium in Barcelona February 26, 2013.  [Photo/Agencies]

BARCELONA - Cristiano Ronaldo crushed Barcelona's treble hopes with two goals in a 3-1 away win for Real Madrid in their King's Cup semi-final second leg on Tuesday to set up a final showdown against Atletico Madrid or Sevilla.

The Portuguese forward became the first player to score in six straight 'Clasicos' away from home when he picked himself up after being felled by Gerard Pique in the 13th minute and struck a powerful low penalty into the corner past Jose Manuel Pinto.

Barca dominated possession but rarely threatened and Ronaldo doubled the lead when he collected a rebound from a 57th-minute Angel Di Maria effort and stroked the ball into the net with Pinto stranded.

It was his 12th goal in 18 appearances against Barca since joining Real in 2009 and his second double in as many games at a stunned Nou Camp.

Real rubbed salt in the wounds of their arch-rivals when Raphael Varane, who netted the equaliser in the 1-1 draw in last month's first leg at the Bernabeu, rose above the defence at a 68th-minute corner and sent a header arrowing into the net off the crossbar.

Jordi Alba pulled one back in the 89th minute but it was far too late for Barca who conceded three goals to Real at home for the first time since a 3-3 draw in March 2007.