Leo Messi of Barcelona reacts after missing the penalty during the first leg of Copa del Rey semifinal between Barcelona and Valencia at the Mestalla Stadium on February 2, 2012.

FC Barcelona and Valencia drew the first leg of their Copa del Rey semifinal 1-1 in Valencia's Mestalla Stadium on Wednesday.

Valencia opened the scoring through Jonas Goncalves, only for Carles Puyol to equalize for Barca with both goals coming in the first half of a highly contested match.

With his side having looked visibly tired last Saturday in Villarreal, Barcelona coach Pep Guardiola chose to rest key players Xavi Hernandez and Dani Alves, with Isaac Cuenca, who signed a new contract with the club starting in attack.

In a full blooded encounter, Barcelona could have been down to 10 men after just 18 minutes after goalkeeper Jose Pinto touching the ball just outside of his penalty area to deny Valencia striker Roberto Soldado a scoring chance.

Valencia did take the lead after 27 minutes when Jonas Goncalves scored following a cross from Jeremy Mathieu from the left.

Barcelona reacted and Valencia keeper Diego Alves made a fantastic save to deny Alexis Sanchez after 33 minutes. Sanchez had been put clean through after a great run by Cuenca.

Alves had been the hero to deny Sanchez, but from the resulting corner he was at fault as he failed to reach the ball allowing Puyol to head home a vital equalizing goal.

The second half saw no letup in the action and Leo Messi went close for Barcelona, before Diego Alves again denied the Argentinean and Gerard Pique headed over from a corner.

Messi then had a chance to score from the penalty spot following a foul on Thiago Alcantara, but Alves redeemed himself by guessing the Barca striker's intentions and saving his shot, which was aimed to the keeper's left. With 17 minutes remaining, Dani Alves, who had come on as a substitute, hit the post after exchanging passes with Messi. Thiago then saw his shot from the rebound charged down.

The result is not a bad one for Barcelona, who will qualify for the final if the score remains 0-0 in next Wednesday's return leg.

Tuesday saw Athletic Club Bilbao win 2-1 away to Mirandes in the first leg of their semifinal clash and the Basque side are now clear favorites to reach the final.