COSTA MESTA, Calif. -- When Austin Ekeler jogs onto the Los Angeles Chargers' practice field on Wednesday, it will be with a lilt in his step and his helmet firmly on his head.

"I'm so excited to put my helmet on," he said Tuesday afternoon. "I might be a little rusty. I want to say I'm going to go out and kill it, but that's not how it works."

His status for Sunday's game at the Buffalo Bills (1 p.m. ET, CBS) has yet to be determined, but Ekeler has spent the last seven weeks in agony and in rehab to repair a nasty injury to his hip and knee. It happened quickly in an Oct. 4 game against the Tampa Bay Buccaneers, when he suffered a hamstring injury so severe, it tore the tendon from the bone.

"It was definitely the most pain I've ever felt," he said.

Ekeler said he was running to his right when a player tried to tackle him low, "and I basically pushed them down and as pushed them down I jumped back." And as he jumped back with his leg fully extended, he felt his hamstring tear.

The pain was so immediate and acute that he couldn't get up on his own. Trainers propped him upright, but Ekeler then told them he had to lay down "because I was about to pass out."

He was taken to the trainer's room, then home. A hospital visit wasn't necessary. What he needed was time.

"I couldn't bring my leg in front of my left hip," he said. "I could only go backwards. So I'd just be inching along backwards. It was three weeks before I could get some forward motion in my leg."

The injury occurred in the fourth game into Ekeler's new four-year, $24.5 million contract extension. He was a sparkplug in the first three-plus games, with 49 carries for 248 yards along with 17 receptions for 144 yards. He was the No. 13-ranked fantasy running back in PPR leagues entering Week 4. But he didn't finish it.

This was the first real season Ekeler felt whole. He entered the NFL in 2017 as an undrafted free-agent who spent his youth doing chores on the family farm and later was a raft guide during a summer in college. The son of a single mom, who was into raising him to be some sort of athlete. He was so determined to make good on what he knew was a promising football career that he chose Division II Western State Colorado University (now called Western Colorado University) when no D-1 offers came and jumped at the chance when the Chargers called in 2017.

He didn't disappoint. For his career, he's rushed 334 times for 1,619 yards and 9 touchdowns while adding 175 receptions for 1,820 yards and another 14 scores.

Overcoming adversity had become his forte and now, with the contract extension, he was set.

Except for being hurt.

Ekeler was taken in for an MRI and was told he needed platelet replacement therapy. That means technicians would remove his blood -- "the most I've ever seen in my life, it made me nauseous" -- spin it with the platelets and then re-inject it into his body to help the healing process.

And then, every day for seven weeks he was at the practice facility in Costa Mesa, sitting in the trainers room with safety Derwin James and running back Justin Jackson, who were also injured. They formed a sort of fraternity. One they never wanted to be part of.

They kept saying don't rush it.

"Even the trainers said you don't want to come back from this early because you'll re-injure it and have to go back. So I'm checking all the boxes," Ekeler said.

He's been discouraged by all of the Chargers' one-score losses but encouraged by rookie quarterback Justin Herbert's success, especially last week against the New York Jets, when the rookie led the Chargers to only their third win.

"He recognized the blitz and got us into a protection and ended up throwing the ball down the field. It was an incomplete pass, but it showed me that he's growing and learning the game," Ekeler said of a Herbert play that stood out. "I got emotional. 'Let's go man', stuff.

"But I feel like a little kid and don't get to play," he added. "This is the longest I've ever sat out in football."

That time out ends Wednesday.

"I'm optimistic because of how my training has gone," he said. "I just want to get back out there and help the team."