Barcelona forward Lionel Messi will be sidelined for almost 10 days after suffering a muscle strain during his team's Primera Liga clash against Atletico Madrid on Sunday. The Argentine forward was substituted at half time in Barcelona's 3-1 home defeat to Atletico after pulling a thigh muscle in his right leg, the Spanish champions' official website reported on Monday. The 18-year-old will miss the Catalan's upcoming crucial league clash against second-placed Valencia on Sunday. Mexican midfielder Rafael Marquez also limped off in the second half of the league encounter after suffering a similar injury. Barcelona will also be without suspended playmaker Ronaldinho for Valencia's game Barcelona are in charge of the Primera Liga table with 52 points, nine points ahead of second-placed Valencia.