Espanyol take the advantage going into their second leg clash next Thursday as Oscar Melendo's late strike settled this tie following Messi's missed spot kick.
Handed a rare opportunity to shine, Vidal's struggles reportedly infuriated Messi as the Spaniard failed to link-up successfully with his team-mates on a bad night for the Catalan giants. Quique Sanchez Flores set his team up to defend deep and frustrate the visitors in the first half and it worked. The visiting side went ahead through Ruben Sobrino in the 66th minute but Portugal global Goncalo Guedes levelled for Valencia in the 73rd.
Messi and Arda Turan were both off target when well placed, while and Gerard Pique saw a goal correctly ruled out for offside.
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Wells' visit was described by the Foreign Office as part of the regular engagement between the two sides on bilateral and regional cooperation.
Third-place Valencia faces an Alaves side which is in the relegation zone but last season made it to the Copa del Rey final against.
Valverde said: "I liked my team a lot". They had a good attitude and had the game under control, but we didn't manage to convert the many chances we had. "In turn, Espanyol defended well, corrected their mistakes and took their chance".
"I've been part of this project for a year and a half, we've picked up 80 points during this time, we're in the quarter-finals, we've beaten Barcelona and the fans are excited. In a week we'll see them at the Camp Nou". It'll be a nice game. "But the team had never been threatened all game apart from a few dead ball situations", he said. "We have to come back". That he scores and signs the victory is fantastic.