Lionel Messi said he wants to win the Copa del Rey with Barcelona in order to ease the pain of the Champions League defeat by Liverpool which ranked among the "worst moments of his career".Speaking at his first news conference in four years, the 31-year-old forward said he was still thinking about the semi-final loss on 7 May when the Reds overturned a 3-0 first-leg deficit."We were hit hard by it," he said."Winning the Copa del Rey will be the best way to end the season."The La Liga champions would complete the domestic double if they overcome Valencia on Saturday (20:00 BST), but Messi warned that defeat would mean the team would "feel a lot worse" than they have done.He added: "We have to apologise for the second half of the match at Liverpool [when they conceded three goals in the 4-3 aggregate loss] not because of the result, but because of how it looked and that we didn't compete. It was one of the worst experiences in my career."The Argentine forward, who also referred to the club's capitulation to Roma in the Champions League quarter-finals last season, defended coach Ernesto Valverde, stating the players were to blame for the Anfield defeat and added that he wanted the Spaniard to remain at the Nou Camp.When asked if he himself was considering leaving Barcelona, Messi responded: "No, no, no."I have had problems with the national team and I still want to keep trying to win something there. The Champions League exit does not make me lose my desire to be here."The club legend could win his seventh Copa del Rey and 21st major trophy with the Catalan giants on Saturday.In an interview with Spanish publication El Pais, Messi's team-mate Gerard Pique said the defeat against Liverpool was a "nightmare".The 32-year-old defender said: "On a mental level some were affected by what happened in Rome.""The first goal came very quickly [in the 15th minute] and suddenly the image of Rome appeared."Then they scored two more goals in quick succession and it starts to look too similar to what happened a year ago. It was very tough, it has been very difficult to pull ourselves back up because the days go by and you can't forget this defeat."

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Barcelona forward Philippe Coutinho is expected to return from injury although he is not guaranteed a starting role as Valverde's side go for a fifth consecutive Copa del Rey.Dutch keeper Jasper Cillessen is likely to start with German first choice Marc-Andre ter Stegen still sidelined with a knee problem.Valencia will be without winger Denis Cheryshev, who also has a knee injury, although he has travelled with the team to Seville's Benito Villamarin Stadium.