World Player of the Year Lionel Messi has been ruled out for up to three weeks by a thigh injury he suffered in Barcelona\'s 2-0 win over Almeria on Saturday. The Argentine had put the Catalans in front with a sublime left-footed strike from 20 yards, but had to be replaced soon after and will now definitely miss Barca\'s Champions League trip to Celtic in midweek as well as Saturday\'s home game against Valladolid. \"The tests carried out this morning have confirmed a small muscle injury in his right thigh,\" said a statement on the club\'s website. \"The approximated time out is two to three weeks, and therefore he will miss the meetings this week against Celtic and Valladolid.\" Luckily for the Spanish champions, following next weekend\'s match there is a two-week break from club duties due to international commitments and Messi is expected to be fit for the trip to Osasuna on October 19. Argentina manager Alejandro Sabella has called up his captain for his side\'s remaining World Cup qualifiers, however with La Albiceleste having already secured their place in next year\'s finals, it seems likely that Messi will miss the meetings with Uruguay and Peru. Messi has been plagued by muscular problems since the end of last season. The 26-year-old suffered a hamstring injury in Barca\'s Champions League quarter-final against Paris Saint-Germain in April and despite briefly returning to action, he never truly recovered from the problem as he sat out the last month of the campaign. And he has also had a minor muscular injury in his left leg earlier this season that forced him off in the first-leg of the Spanish Super Cup and to miss the league trip to Malaga in August. However, he has still scored 11 times in nine matches so far as Barcelona have made their best ever start to a Spanish league season. Source: AFP