KANSAS CITY, Mo. - Chiefs safety Eric Berry is gearing up for a fight after a mass was found in his chest following last week's game in Oakland. He was placed on the non-football injury list Monday, and trainer Rick Burkholder said Berry may have lymphoma.

Burkholder said doctors are "75 per cent" of the way toward a definitive diagnosis, and that Berry was on his way to Atlanta to be examined by specialists at Emory University.

"They may do further scans. In all likelihood, they'll do a biopsy of one of the lymph nodes or the mass," Burkholder said. "We'll be able to give you more information in the next couple days."

Burkholder spoke during a sombre news conference attended by Chiefs coach Andy Reid, general manager John Dorsey, team president Mark Donovan and chairman Clark Hunt. Berry issued a statement in which he said he was "in shock" but promised to battle the illness.

"I understand that right now I have to concentrate on a new opponent," he said. "I have great confidence in the doctors and the plan they are going to put in place for me to win this fight. I believe that I am in God's hands and I have great peace in that."

The 25-year-old Berry, an All-Pro in 2013, began feeling discomfort during Thursday night's loss in Oakland. He was examined by team physicians Cris Barnthouse and Michael Monaco, and they recommended further tests. The mass on the right side of his chest was discovered Friday night.

Berry underwent more tests, including a CT scan and blood work, over the weekend. He met with the team on Monday morning, shortly before flying to Atlanta for a consultation with Dr. Christopher Flowers, an associate professor at Emory and a leading expert in lymphoma.

Berry has no history of cancer, Burkholder said, and a routine physical over the summer came back clean. In fact, Berry is considered one of the healthiest players on the team, usually absent from the locker room during periods of media availability because he is in the training room.

"He had an opportunity to address the team and feel their love and support, which I think is crucial," Reid said. "When you get in these situations, you hunker down and battle for your life, which is what you do. You have to be in a certain frame of mind, have certain support to back you up, and Eric has that with his family and also the Chiefs."

Berry, who grew up near Atlanta, is expected to be evaluated over the next few days. The Chiefs (7-3) will head into a pivotal AFC West showdown with Denver on Sunday night without him.

"We're really just a microcosm of life," Reid said, "is what we are in this building. And a small family — maybe a big family, you could say. So you have the support, people standing up, and they work through the emotional part of it, support each other and most of all support Eric."

Berry was the fifth-overall pick in the 2010 draft, and made an impact almost from the start, earning Pro Bowl honours his rookie season. He missed nearly all of his second year after tearing a ligament in his knee, but returned to start every game the following season.

He was voted All-Pro last season after tallying 3 1/2 sacks, recording three interceptions and scoring two touchdowns. He also recovered two fumbles while making 81 tackles.

This year had been a disappointment. Berry sustained a high ankle sprain in Week 2 against Denver, sidelining him for the next six weeks, and he's struggled to get back up to speed.

Now, the kind of news that puts even the worst of seasons into perspective.

"Eric is as strong and courageous as anyone I know," said his agent, Chad Speck, who saw Berry in Oakland and spoke to him after learning of his illness Saturday. "When I spoke to him that night, I felt his strength and his faith through the phone."

The Chiefs have certainly experienced plenty of heartache over the years.

In 1983, popular running back Joe Delaney drowned while trying to rescue three children who were struggling in a Louisiana pond. In 2000, linebacker Derrick Thomas died of injuries sustained in an auto accident. And two years ago, linebacker Jovan Belcher shot to death the mother of his infant daughter before driving to the team practice facility and killing himself.

"I don't think you're ever equipped necessarily to handle what life throws at you," said Hunt, whose family owns the Chiefs, "and certainly this was completely unexpected. But I do think we have a culture where we respect and support each other, and really that's the most important thing."

Hunt said he had a chance to speak with Berry on Monday and offer his support.

"When you have someone who has been with you for a number of years, and I've had a chance to get to know him personally and he's been such a leader for our football team, it probably does pull at the heart strings more," Hunt said. "But whether it's an employee in the front office or someone on the field, when they're going through a tough time like this, we want to be there."