MADRID, August 21 (Reuters): Atletico Madrid winger Vitolo is set to miss between two and four weeks after suffering a knee sprain during his team's 1-1 La Liga draw at Valencia on Monday. "Vitolo finished the game which we played at Mestalla against Valencia with pain in his left knee," Atletico said in a statement on Tuesday. "The report from club medics indicates he has suffered a grade two knee sprain." Although the club did not state the estimated length of Vitolo's absence, this type of injury can take up to a month to heal. New signing Gelson Martins, who impressed as a substitute against Valencia, may get more playing time in the coming weeks.