MADRID (AFP) - Argentine superstar Lionel Messi on Saturday became the first player to score 50 goals in a Spanish season as Barcelona and arch-rivals Real Madrid both triumphed ahead of their mouth-watering Champions League duel. Messi reached his latest landmark when he found the target three minutes from time in his team's 2-0 win over Osasuna as Barcelona maintained their eight-point lead at the top of La Liga. He had already equalled the previous best mark of 49 goals scored by Real Madrid legend Ferenc Puskas when he netted in the 1-1 draw against Real last weekend. Now Messi has 31 goals in the league and nine in the Champions League after finishing with seven in the King's Cup and three in the Spanish Super cup. Earlier Saturday Real crushed Valencia 6-3 to set the foundation for Wednesday's Champions League semi-final first leg clash at their Bernabeu home. In midweek, Barca's hopes of a treble had come to an end when Real beat them 1-0 in the King's Cup final, but coach Pep Guardiola shrugged it off saying that the league is their main priority. However, ahead of another 'clasico' in Europe, Guardiola chose to leave the likes of Messi, Xavi Hernandez and Andres Iniesta on the bench against Osasuna. The impressive Jeffren Isaias supplied the 24th minute cross for Spain international David Villa to end one of his worst spells in front of goal when he fired passed the keeper after having gone eleven matches and two months without scoring. In the second half Barca tightened up and substitute Messi came on to secure the three points and his place in the record books. "It wasn't a very strong performance from us. Osasuna are always a difficult team and we had players who don't play that often. It was important for Villa to get his goal to boost his confidence," said Guardiola. Looking ahead to the game with Real he added: "If we go to the Bernabeu aiming to defend they will take advantage. We need to go and score goals even though we have problems with injuries. At the moment not many people would back us as Madrid are playing a lot better." A second-string Real side romped to a 6-3 win over Valencia. Coach Mourinho fielded just Casillas and Carvalho from the side which beat Barcelona in the final of the King's Cup as he also looked to rest his players. Argentina striker Gonzalo Higuain made the most of his opportunity with a hat-trick while Brazilian star Kaka grabbed a brace.