Superstar winger To'o left the Panthers' 30-10 defeat of South Sydney on Friday night after clashing knees with Rabbitohs hooker Peter Mamouzelos in the second half.
He consulted a doctor at full-time and will be monitored over the weekend before the Panthers determine his availability for next week's clash against Wests Tigers in Parramatta.
The winger remains hopeful of lining up as the resurgent Panthers look to make it seven wins in a row.
"There are good signs so far," he said.
"It was a bit of a touchy feeling; (the collision) was definitely on the right spot."
Friday night's injury was an aggravation of a knee issue suffered earlier in a season of fitness setbacks for the affable NSW winger.
A hamstring issue prevented To'o from lining up for Penrith in the Las Vegas season opener and he has struggled for continuity ever since.
The 26-year-old has played only eight NRL games in 2025 and was under an injury cloud for the second and third State of Origin games with hamstring and knee problems, respectively.
On both occasions, he ultimately took the field to prove one of the Blues' best in losing efforts.
To'o said it was his job to push through the pain as the Panthers look to lock in a finals spot with a favourable fixture over the coming weeks.
"I'll always back myself to keep going," he said.
"It's part of the job, you'll always be busted and bruised, but never broken."
On Friday night, Keaon Koloamatangi (ankle) and Peter Mamouzelos (head knock) became the latest in a long line of Souths players to fall victim to injuries this season.
To'o was relieved the Panthers have a mostly clean bill of health on the home stretch of the regular season, having lost key players in recent years at around this time.
Nathan Cleary notably needed time on the sidelines to recover from a shoulder injury ahead of last year's finals, with Jarome Luai also nursing a shoulder problem late in the 2023 campaign.
Other than To'o, the only Panthers under injury clouds for round 21 are Liam Martin, who is expected to shake off a wrist injury, and out-of-favour hooker Soni Luke (biceps).
"We've been unlucky the last couple of years with injuries late in the season. It's good to know," To'o said.
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