Oakland Raiders starting left guard Langston Walker had emergency surgery to repair a hemorrhage in his stomach. Walker complained of pain in his abdominal area Tuesday, then the team's training staff quickly got him to a doctor. The 6-foot-8, 345-pound lineman had an arthroscopic procedure later in the day and is expected to be sidelined a minimum of six weeks. ``From what I understand, it could be considerably longer,'' coach Norv Turner said after practice Wednesday. ``It's a serious deal. He is OK. That's the No. 1 concern. It's just unfortunate for our football team. But he's very fortunate that he's all right and that they found it when they did so that it didn't become major.''