FRISCO, Texas (AP) — Travis Frederick will not go on injured reserve initially as he battles a condition that affects the nervous system, although the Dallas Cowboys still don't have a timetable for the return of their four-time Pro Bowl center.

Coach Jason Garrett said Monday that Frederick hasn't had any "drastic setbacks" while getting treated for Guillain-Barre syndrome. The disorder attacks nerves and causes weakness in various parts of the body.

Joe Looney is expected to start when the Cowboys open the season Sunday at Carolina.

The 27-year-old Frederick traveled with the team to the final preseason game in Houston and is attending meetings. He has started all 83 games, including three playoff games, over five seasons. A move to IR would force Frederick to miss at least eight games.

"It's been positive since he started his treatments," Garrett said. "And that's given us cause to be optimistic. He's working out on his own. He's been able to handle the work so far. From my perspective, the information that I've gotten, there hasn't been any drastic setbacks in any way."

The Cowboys added depth on the interior line by claiming center Adam Redmond on waivers from Buffalo and acquiring Kansas City backup Parker Ehinger in a trade. Ehinger was a fourth-round pick two years ago.

Dallas doesn't want to move four-time Pro Bowl right guard Zack Martin to center, but he is the emergency option. Martin injured a knee in the second preseason game against Cincinnati but says he will be ready to start against the Panthers.

Frederick hasn't spoken to reporters since announcing his diagnosis almost two weeks ago.

"He reached out to me and said, 'Coach, would you mind if I came to Houston? I'd like to be part of the visit to NASA and I'd like to be part of the team when we play on Thursday night,'" Garrett said. "I said, 'Would I mind? Are you kidding me? I'd absolutely love to have you be a part of it.'

"He's been very proactive and he's taken the initiative of being back and being part of our team and trying to be involved in everything that we do short of going out on the practice field."

Frederick, Martin and left tackle Tyron Smith — all first-round picks and all Pro Bowlers each of the past four seasons — have anchored a line that the Cowboys hope can make them a run-first team with Ezekiel Elliott, the NFL rushing leader as a rookie in 2016.

La'el Collins is going into his second year as the starter at right tackle, and rookie second-round pick Connor Williams is at left guard.

NOTES: The Cowboys placed WR Noah Brown (hamstring) on IR and brought back WR Deonte Thompson in his place. Thompson was among the final cuts after signing as a free agent in the offseason, but Garrett said the Cowboys intended to bring him back. Thompson was slowed by an Achilles injury most of training camp. ... Rookie RB Bo Scarbrough of Alabama, a seventh-round pick, was signed to the practice squad.

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