ALAMEDA, Calif. (AP) – 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.”

Walker’s symptoms initially pointed to him having appendicitis, but doctors discovered internal bleeding. He will remain in the hospital for four or five days, Turner said.

The 26-year-old Walker, a talented kick blocker, is in his fourth NFL season after the Raiders selected him out of nearby California in the second round of the 2002 draft.

Walker had not previously said anything about stomach problems, but Turner believes it was probably football-related, such as an injury players get that they don’t know about right away.

Most of Walker’s teammates found out about his condition when they showed up for work Wednesday, and some were planning to visit him in the coming days before leaving Friday for Tennessee. The coaching staff hoped to see Walker on Thursday.

If healthy, Brad Badger would play in place of Walker on Sunday against the Titans, but Badger is nursing a knee injury. Jake Grove, who began the season as the team’s starting center, took most of the snaps at left guard during Wednesday’s practice. Grove expects to start this Sunday after having arthroscopic surgery on his right knee Oct. 3.

Turner said the Raiders might have to consider bringing in another lineman if Walker is out an extended period.

AP-ES-10-26-05 2015EDT