The 32-year-old key forward, who has managed just eight games over the past two seasons because of injuries, had been enjoying a strong summer training block.
But Tigers assistant coach Steve Morris told reporters Lynch was hurt in a collision with a teammate at Punt Road on Friday.
"Lynchy can't take a trick," Morris said.
"He's had an outstanding eight weeks of training and he's firing on all cylinders.
"I've found myself on the bump bag a few times and he's training with some real purpose.
"So (the concussion) is a bit of a speed bump for him, but he's in really good nick and we hope to see him back in the really near future."
Lynch has played just one game since March last year, having been plagued by hamstring injuries last season.
Richmond remain hopeful he will be fit to play in preseason hit-outs before they open the new campaign against Carlton on March 13.
Morris also backed suspended star Noah Balta to have an impact after the key defender serves his four-match ban, stemming from a violent off-field altercation.
Balta, 25, this week pleaded guilty to assault over the incident in the NSW-Victoria border town of Mulwala on December 30.
"We've asked him to really dig in to his training over the last little bit and what I've seen is a guy who's really committed to earning the trust of his teammates," Morris said.
Noah Balta has been training the house down as he tries to win back the trust of his teammates. (Julian Smith/AAP PHOTOS)
"He's put everything out on the table over the last few weeks, doing extra sessions, and he knows that he's got to get himself really red-hot fit.
"He's a really important player to our team and our club, and I think he's doing a really good job at the moment under the circumstances that he's facing."
Jacob Koschitzke has been training in defence as Richmond seek tall cover for Balta during the early rounds of the season.
The versatile key position player was picked in the 2018 Under-18 All-Australian as a defender before being moved forward during his three years at Hawthorn.
Koschitzke also played predominantly in attack during his first season with the Tigers, kicking 12 goals in 14 games last year.
"We know what he's going to give us up forward but we want to find out whether there's something more that we might be missing down back," Morris said.
"Obviously with Noah missing the first part of the season, it's important that we've got some insurance there.
"Kozzie's putting his front foot forward and doing a really good job down back.
"He certainly understands the system really well, so I'm looking forward to seeing his progression down back over the coming weeks."
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