RENTON, Wash. (AP) — At various points during his recovery, when he was traveling to Germany and Switzerland and England to try out the latest treatments, Brandon Marshall spent nearly as much time fighting doubt as he did trying to overcome his injuries.

His world is now centered in Seattle, the sixth stop in his 13-year career. It's a stop where he may start and will likely be a heavy contributor when the Seahawks open the regular season Sunday in Denver, the place where he first became a star.

"I'm a competitor. That's why I'm here," Marshall said. "I think the reason why I'm still playing is that I felt that I never arrived. I always feel like you can get better."

This isn't the spry Marshall that became one of the top receivers in the league while in Denver and Miami. It's not the version of Marshall that caught 109 passes and 14 touchdowns just three seasons ago with the New York Jets.

This version of Marshall is 34 years old, coming off a major ankle injury and toe surgery that cost him the majority of the 2017 season with the New York Giants. He's a complementary player who fills a need for the Seahawks with his 6-foot-5 frame and could become the red-zone target Seattle had in recent seasons with Jimmy Graham.

At this point of his career, Marshall has the highest standards for even the smallest things. Jaron Brown learned that in training camp when during a drill he lined up in the wrong spot.

"He kind of got mad at me for a second and he didn't talk to me for that whole period. I didn't know what was going to happen," Brown said with a laugh. "It was OK. ... I think at this point he wants to get everything right and he critiques himself so hard. I understand it because I'm that way too but it was funny to see him get a little mad at me."

He's also become a sounding board for younger players seeking advice or ideas. Considering he's the second-oldest player on Seattle's roster — only kicker Sebastian Janikowski is older — that means it could be anyone.

"His vast knowledge of the game is incredible. I was just picking his brain earlier about some things, about offenses and what he's seen in his history," wide receiver Doug Baldwin said. "Obviously the physical presence he brings to the field, he's extremely gifted with that, with his size, but he is so nimble, so quick and it's fun to be able to go back and forth with a guy who has so much knowledge about the sport. I think that part of it, just in itself, is going to be a huge positive."

What Marshall can bring — if healthy — is something Seattle has wanted for years.

Coach Pete Carroll has sought a big wide receiver throughout his time with the Seahawks and he's only had that kind of offensive weapon in small spurts.

Graham was that way once he returned from a major knee injury, but it was mostly just around the end zone that Seattle figured out the best ways to use him. Mike Williams had a breakout season with the Seahawks in 2010, but it was just that one season.

His health is going to be the biggest question for Marshall. Once he shook a slight hamstring strain in training camp, he demonstrated the skills and talent that have made him one of the top pass catchers in the game. The real test of what Marshall has left begins Sunday.

"I'm still trying to prove myself to not only the world but most importantly my teammates and my coaches here," Marshall said. "On paper it's a 34-year-old receiver with two down years. Every day I go out there I remind myself I want to prove to (Russell Wilson) what type of receiver I am and what he has out there."

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